A former Conservative MP has insisted he is the victim of a "homosexual witch hunt" after he was questioned for a second time by detectives investigating historical claims he was involved in the murder and sexual abuse of children.

Harvey Proctor said he was "completely innocent" of allegations that he murdered two young boys and was linked to the death of a third, as he called for the complainant - known by the pseudonym "Nick" - to be stripped of his anonymity.

The 69-year-old former politician was interviewed under caution on Monday by Metropolitan Police officers working on Operation Midland, the inquiry launched following historical allegations of a VIP paedophile ring.

Speaking at a packed press conference in central London on Tuesday, Mr Proctor laid out graphic details of the claims made against him and revealed former prime minister Sir Edward Heath and ex-home secretary Leon Brittan had been named among his "alleged co-conspirators".

He said: "They amount to just about the worst allegations anyone can make against a person ... multiple murder of children, their torture, grievous bodily harm, rape and sexual child abuse.

"I'm completely innocent of all these allegations.

"I'm a homosexual. I'm not a murderer. I'm not a paedophile or pederast.

"This whole catalogue of events has wrecked my life."

Mr Proctor, who represented Basildon in Essex from 1979 to 1983 and Billericay from 1983 to 1987, was not arrested when he was questioned by police on Monday.

He told reporters that the complainant, "Nick", had stated he was "the victim of systematic and serious sexual abuse" by a group of adult men over a period between 1975 to 1984.

Mr Proctor said one of the homicide allegations was that "Nick" claimed to have witnessed him repeatedly stabbing a boy with a knife over 40 minutes before raping and strangling him at a house in Pimlico/Belgravia, London, in 1980.

A second homicide allegation was that Mr Proctor and two other men beat a boy to death at a house party in central London in 1981/82, he added.

Mr Proctor said "Nick" claimed the former MP was not "directly involved" in a third homicide accusation when a boy was said to have been hit by a car in 1979.

But the complainant believed the alleged group of abusers was responsible for the attack, he added.

Mr Proctor said another claim was that he threatened to castrate "Nick" with a penknife but was persuaded not to by another man, whom it was suggested was Sir Edward.

Other allegations of sexual abuse were said to have happened at Dolphin Square - claimed to be the centre of the alleged paedophile ring - the Carlton Club, a swimming pool and a large townhouse, he added.

Mr Proctor branded the allegations against him as "ludicrous".

He said: "I should be arrested, charged and prosecuted for murder and these awful crimes immediately so I can start the process of ridiculing these preposterous allegations in open court.

"'Nick' should be stripped of his anonymity and prosecuted for wasting police time and money.

"The paranoid police have pursued a homosexual witch hunt on this issue egged on by a motley crew of certain sections of the media and press and a number of Labour Members of Parliament and a ragbag of internet fantasists."

Mr Proctor said he had never owned a penknife, which "Nick" had given to police as evidence, and said Sir Edward, who died in 2005, "despised" him.

The ex-MP insisted he did not know Jimmy Savile, after "Nick" claimed the former MP attended sex parties with the late disgraced DJ.

He also denied visiting Elm Guest House, which has been the centre of the sexual abuse allegations, and claimed he had not recognised a picture of the complainant.

Mr Proctor, who was interviewed under caution for the first time in June, said Metropolitan Police Commissioner Sir Bernard Hogan-Howe should resign "for the sin of hypocrisy" over claims the media were tipped off about a search of his home in Leicestershire in March.

Mr Proctor called for Detective Superintendent Kenny McDonald, head of Operation Midland, to resign or face the sack after claiming that he believed what "Nick" was saying was "credible and true".

He said the operation should be "wound up" at the earliest opportunity and Labour MP Tom Watson should apologise for using parliamentary privilege to discuss claims of a Westminster paedophile ring.

Superintendent Sean Memory of Wiltshire Police, which is leading the inquiry into claims against Sir Edward, should also resign after making a statement outside the former PM's home in Salisbury, he added.

Mr Proctor left parliament in 1987 after pleading guilty to acts of gross indecency.

Operation Midland was launched by the Met last November following allegations that boys were sexually abused by a VIP paedophile ring centred around Westminster more than 30 years ago.

There were claims that sex parties involving boys below the age of consent were held at the exclusive Dolphin Square apartment block near the Houses of Parliament.

Scotland Yard said it was not commenting following the press conference, which took place at the St Ermin's Hotel just yards from the force's headquarters.

Conservative MP Sir Alan Duncan moved to defend Mr Proctor, who is one of his constituents.

Sir Alan said the former politicians who have been accused will "mostly be vindicated" and called on the police to sack officers who have leaked information about arrests to the press.

He said: "It looks as though lots of self-righteous goodies are going to turn out to be baddies and those accused will mostly be vindicated.

"Police tip-offs to the press about arrests should be investigated and lead to sackings.

"Who is going to compensate those who are living who have been so severely traduced?"