The father and uncle of murdered toddler James Bulger have begun a legal battle for information about one of the killers, Jon Venables, to be made public.

Ralph and Jimmy Bulger want to change a lifelong anonymity order made when Venables was released in 2001.

Lawyers for the pair argue the public is unable to examine how the state has handled Venables’s rehabilitation because no information about his life since his conviction in 1993 can be discussed.

Despite numerous rumours about Venables’ new life being regularly published across the internet, anyone who releases anything which could identify Venables’ new name or location is liable to be prosecuted for contempt of court.

In 2010 Venables was returned to prison and given a new sentence of two years after he was caught downloading and sharing images of child abuse, prompting calls from James Bulger’s mother, Denise Fergus, for his anonymity to be removed.

He has also been arrested on suspicion of affray after a drunken fight, been cautioned for possession of cocaine, and reportedly revealed his true identity to friends on numerous occasions.

Venables was released from prison in 2013 and given a new identity but was recalled again in 2017 over possession of indecent images of children.

In February 2018 he pleaded guilty and was sentenced to three years and four months in prison.

On multiple occasions, people who have shared photographs or other information online which purported to identify Venables as an adult have been prosecuted and convicted, mostly being given suspended prison sentences.

Solicitor-advocate Robin Makin, representing the Bulgers, told the High Court on Tuesday the situation with Venables was “unprecedented”.

“We now have a child murderer who has, as an adult, committed two sets of serious sexual offences and is undoubtedly a danger to the public.”

He argued the state had failed to properly monitor or rehabilitate Venables, but this could not be properly scrutinised in public because revealing any information about his offending or incarceration since 2001 was unlawful.

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“The point is that [Venables] has been trained by the state to be dishonest and hide his identity, and to no doubt develop techniques for dealing with such matters.

“In terms of the alleged ‘robust monitoring’ of Venables ... how could there have been robust monitoring when the offending went back over a period of months?”

In order for Ralph and Jimmy Bulger to “exercise their rights as victims and to deal with the process going forward” the anonymity order must be limited so that details of the killer’s former identities, addresses and prisons up to 2017 could be safely published.

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Similar disclosure happened at his first re-arrest in 2010, Mr Makin argued, which had not “damaged him in any way”.

Details about his current life are easy to find online in any case, he added.

Robert Thompson, who was Venables’s accomplice, is not having his lifelong anonymity challenged.