Everything revolves around the sultan’s whims. Berlusconi’s silent security guards even looked on as Berlusconi pawed and groped D’Addario as they sat on a sofa together – as discreet as court eunuchs in ancient Constantinople. She didn’t like it, she now says, but like any good courtesan, she kept quiet – this time it wasn’t money buying her silence but the tawdry offer of the premier’s help with a town-planning problem.

D’Addario, a 42-year-old call girl from the southern town of Bari, is only one of a number of women allegedly introduced to Berlusconi by southern businessman Gianpaolo Tarantini and paid by Tarantini to attend the premier’s parties and, on occasion, provide him with sexual services. What makes her exceptional, however, is that she taped conversations with Berlusconi that make the Camillagate tapes between Prince Charles and his lover seem an innocent teen romance.

D’Addario allegedly spent the night with the prime minister at his private Rome residence on the evening that Barack Obama was elected president of the United States. She has already described the night’s events in a number of newspapers opposed to Berlusconi, notably the news magazine L’Espresso and the left-wing paper La Repubblica, as well as in testimony to Bari prosecutors investigating Tarantini for allegedly abetting prostitution and corruption.

Newspaper readers were therefore familiar with her claim that she had had sex with the premier on Putin’s bed, after having her feet licked by a pet dog, a gift from Barbara Bush. Obama, Putin, the Bushes: the escort from Bari had gained unusual intimacy with contemporary history, with no vetting and minimal delay.

D’Addario says she had shared the early part of the evening with a bevy of attractive young women, dressed in black and with light makeup, just as the prime minister liked it. Two of the girls were in trousers, she claimed – they were lesbians who always worked as a couple.

In response to D’Addario’s claims, which have eaten away at his authority and support, Berlusconi initially said he had no recollection of ever meeting the woman, but mobile phone photographs of the premier’s Palazzo Grazioli private apartment and audio tapes of the night have now forced him to concede that inappropriate individuals may have had access to his inner circle.

On Wednesday Berlusconi explained that mobile phones had not been confiscated from visitors because his own presence was sufficient guarantee that nothing untoward would take place on the premises.

“We let everyone keep their mobiles because as long as I am present nothing inelegant can happen, because I am a person of good taste, culture and elegance,” he said. That assurance rings somewhat hollow in the light of some of D’Addario’s intimate recordings posted last week on the L’Espresso website. The transcripts and audio recordings offer a lurid insight into the prime minister’s sexual preferences and practices, the kind of information that would rarely seep into the public domain and does little to bolster his reputation for good taste and elegance.

Berlusconi’s lawyer, Nicolo Ghedini, has suggested the tapes may have been tampered with, and if they were genuine their publication was illegal.

In one of the more embarrassing tapes, D’Addario appears to compliment Berlusconi on his ability to postpone the moment of orgasm.

“A young man would have come in a second... Young men have a lot of pressure,” D’Addario said.

Berlusconi allegedly responds that the problem runs in families. “You should have sex with yourself... You should touch yourself often,” he suggests.

The background to this alleged modern version of pillow talk emerges from another tape posted on the magazine website. In it Tarantini explains to D’Addario that he had already given her €1000 and that she would receive a further present from the prime minister if she agrees to spend the night with him.“By the way, he doesn’t use a condom, OK?”

As it happened, it wasn’t okay. “Just think how many people have spent the night,” D’Addario protested, insisting that she was “not going to do it without protection”.

In the event, D’Addario says, she was not paid in cash but promised the prime minister’s help in overcoming planning restrictions that were holding up a construction project she had invested in near Bari. It was Berlusconi’s failure to keep this promise that appears to have turned D’Addario against him.

Berlusconi’s supporters say that even if these tapes are authentic they are politically irrelevant, part of a vitriolic personal attack by a desperate opposition unable to mount a convincing political challenge to a popular and effective government.

The centre-left opposition has, in fact, trod very gingerly around this issue, leaving it to the L’Espresso/La Repubblica publishing group to carry the torch. Democratic Party leader Dario Franceschini, facing a strong internal challenge to his party leadership, had his fingers burned when he asked rhetorically whether Italians would be happy to have someone like Berlusconi bringing up their children. The question elicited a furious response from all five of Berlusconi’s offspring, extolling the prime minister’s parental virtues.

L’Espresso and La Repubblica insist their moralising campaign has a real political significance: a premier who lies about the irregularity of his private life lays himself open to blackmail and provides a bad example to the country.

“The premier seen through the bedroom keyhole is completely different from the conservative statesman who passes laws based on the values of God, Fatherland and Family,” L’Espresso observed in a commentary accompanying its latest “Barigate” revelations.

The long-running sex scandal that has swirled around the prime minister has now become the subject of an instant book, Papi: A Political Scandal. The title uses the intimate name allegedly used for Berlusconi by the young members of his harem, which first emerged from the mouth of Noemi Letizia, a teenage aspiring model whose friendship with the premier so infuriated his wife that she charged publicly that the prime minister was “not well”.

Marco Travaglio, a leading political commentator and one of the authors of the book, denies being obsessed by the premier’s private life. “I couldn’t care less about the Cavaliere’s [the Italian moniker for the Cavalier leader] sex life. I’m concerned about the fact that he’s blackmailable. He’s the prime minister, so he can’t afford to be,” Travaglio told the online newspaper ­www.affariitaliani.it.

Travaglio said Berlusconi’s private life had started to run off the rails in the summer of 2006, after he lost a general election. He said he and his two co-authors had decided to write the book after witnessing a commentary by the editor of TG1, the flagship news programme of the state broadcaster RAI, in which he justified the self-censorship exercised in regard to Berlusconi’s domestic woes.

“We realised that millions of Italians who receive their information from the television don’t know anything about these stories,” he said. Many commentators believe Berlusconi was able to ride out the sexual allegations because he sparkled, statesmanlike, at the recent G8 summit in L’Aquila.

“The G8 truce is over, when Berlusconi donned the mantle of world statesman. Now his old demons are back and Repubblica, L’Espresso and the foreign press are tracking his every move,” said Salvatore Aloise, a veteran observer of Italian politics.

“He tries to shrug off the scandal with a joke and continues to be convinced that he’s the perfect representative of the Italian dream. He thinks he will never be called to account, but he can’t rest easy.”

Last week the political signs for Berlusconi were not good, as his approval ratings dipped worryingly below 50% following the scabrous L’Espresso’s publication of the latest revelations about the prime minister’s private life. An opinion poll published by the left-leaning daily La Repubblica – which has consistently criticised the prime minister over allegations that he consorted with underage girls and prostitutes, showed just 49% of the Italian electorate approve of Berlusconi’s conduct. The fall in popularity could be a first indication that Italians are beginning to tire of the sexual scandal that has dogged the prime minister for the last three months, since his wife, the former movie starlet Veronica Lario, announced she was seeking a divorce.

Berlusconi responded with characteristic ebullience, insisting that his own poll figures showed an approval rating of 68%, that personal attacks only damaged the opposition, and that the government was working miracles for the benefit of the nation.

Speaking at a ground-breaking ceremony for a new motorway in northern Italy on Wednesday, Berlusconi acknowledged that he wasn’t a saint, joked that the north was full of beautiful girls, and boasted that the government would be ready to rehouse 20,000 of the Abruzzo earthquake victims in comfortable, anti-seismic houses by the end of November. “This is a miracle, because in China, where there has been an earthquake, they are still living in tents and shacks,” he said.

It was the classic Berlusconi riposte: the allegations against him are laughable and irrelevant, the government should be judged on its sterling achievements, and the Italians love him just the way he is, anyway.

The La Repubblica poll may just begin to undermine some of that self-confidence. No leader of a major industrialised country – with the possible exception of Bill Clinton – has had to endure such prolonged media intrusion into the details of his private life. And few could boast such a colourful one as that which has been coming to light in the pages of L’Espresso.

Most worrying for Berlusconi is a potential desertion by Catholic voters, disgusted by the reports of his personal conduct and influenced by the voices of criticism that are beginning to be raised by members of the Catholic establishment.

Berlusconi’s aides sought a meeting with Pope Benedict XVI to round off the G8 summit but were reportedly rebuffed. And there have been reports that Catholic authorities are reluctant to approve a public prime ministerial pilgrimage to the shrine of St Padre Pio in Puglia, that might help to mend fences with the Catholic electorate. A worrying sign of Catholic impatience with the premier’s behaviour emerged yesterday when L’Avvenire, the newspaper of the Catholic bishops’ conference, published a critical editorial and a series of hostile readers’ comments. One of the readers, Fiorella Pasotti, said she had listened to the sex tapes on the L’Espresso website and wished the newspaper was firmer in its criticism of “the brazenness of our prime minister, who appears to be anything but God-fearing”.

The editor of L’Avvenire, Father Dino Boffo, replied that citing positive opinion polls was no justification for Berlusconi’s behaviour. “This affair... continues to give little or no pleasure to a large proportion of the real country,” Boffo wrote. Not everyone however believes that the sexual scandal will do the prime minister long-term harm. Many Italians are secretly impressed by the vitality of the 72-year-old premier, and envious of the professional and personal success that enables him to break the rules and get away with it.

“Knowing the way Italians think, I don’t believe these scandals will seriously erode his electoral support,” said Gianpaolo, a Rome-based civil servant reluctant to be fully identified. “I think he has been hurt on a personal level and in his international standing, but his popularity remains virtually unaffected. Unless much worse emerges, the electorate will soon tire of this story.”

The remarkable political career of the media magnate who developed his seductive charms as a cruise ship crooner now seems poised on a knife-edge. The discredit brought by D’Addario and her colleagues could see it slither into an inexorable decline, or the Barigate scandal could be remembered a year hence as a minor irritant in a long and controversial career.

Perhaps the most worrying aspect of the affair is that Berlusconi is almost unique among western leaders in his ability to deceive himself and to spread his view of events to the country he rules through a largely subservient domestic media. The last word on his future will fall to a much-manipulated Italian public, and their verdict, right now, is almost impossible to guess. Though many believe that if there is one thing that will take down a man like Berlusconi, it’s a beautiful woman – his greatest weakness and perhaps fatal flaw.