A high-risk sex offender assaulted a neighbour just days after being released from jail while police were constantly monitoring him, a court has heard.

The Tayside force launched the multi-agency initiative, codenamed Operation Jubilee, to manage the release of Thomas Shannon, 21, from prison in January.

Yesterday, at the High Court in Dundee, Shannon pled guilty to sexually assaulting his victim at a flat in the city's Lochee area. He also admitted breaching a Sexual Offences Prevention Order (Sopo)

She had gone to the property, unaware of his lengthy record of sex offending, which had begun at the age of 14.

Tayside Police had installed a covert remote listening device in his flat, but despite that he targeted her just two weeks after being freed, the court heard.

The woman, who cannot be named for legal reasons, rang Shannon's entry buzzer after getting locked out of the flat building, the court heard. Shannon allowed her in, with police seeing her on CCTV. They went to the scene, knowing Shannon was in the building, but found no trace of the woman at his address. But later the woman went to his door, where he invited her in. Shannon then told the woman he had been in prison and needed sex.

Advocate depute Gillian Wade told the court: "Constables were monitoring the covert listening device. The accused's behaviour changed significantly and he began cuddling her, kissing her on the neck and groping her over her clothing."

Miss Wade said Shannon then exposed himself to her and refused to let her leave.

Police heard the woman pleading with Shannon to "leave me alone" and "let me get out" via the listening device. Shannon was later arrested and interviewed by police – but denied attacking the woman.

Shannon, 21, a prisoner at HMP Perth, pled guilty to a charge of sexually assaulting the woman on February 12 this year at his flat.

He further admitted breaching a sexual offences prevention order made on January 26 – the day before he was released from Polmont Young Offenders Institution.

Shannon has a horrific list of previous convictions for sex offences.

At the age of 14 he was placed in a residential unit in Fife that specialises in dealing with people who display "inappropriate sexual behaviour".

In April that year, he was charged with lewd and libidinous practices, which was found proven at a Children's Hearing.

In May 2006, he was charged with assault with intent to rape a female member of staff within the unit.

He was moved to another unit in Glasgow, and later received a 32-month jail term with a three-year extended sentence.

In August 2007, he was charged with indecent assault on another member of staff and received another 18-month term.

In June 2008, he was served with a Sopo, but breached that just two months later, receiving another four-year term – reduced to two years and nine months on appeal.

His latest crime took place just 16 days after his release this year.

Shannon had been placed in the property in Dundee as part of the Multi Agency Public Protection Arrangements, which aims to manage sex offenders when they are released back into the community.

Defence solicitor advocate Gerry McClure reserved his plea in mitigation to a later sentencing date.

Judge Lord Doherty deferred sentence until October 26 at the High Court in Edinburgh.