James Bulger killer Jon Venables was taken back into custody after he was accused of committing a sex crime, it was reported yesterday.

It was initially reported that Venables (27) was recalled to prison after a fight at work but a British tabloid newspaper reported that was untrue.

It reported it had uncovered the "exact details" of the alleged offence but was unable to publish them in full because it might lead to Venables' new identity being uncovered.

British?justice minister Jack Straw said the recall to custody involved some "extremely serious allegations" as he prepared to meet the dead boy's mother. Denise Fergus has demanded to know what the convicted murderer did to be sent back to prison and she is expected to meet Straw in the coming days.

Justifying his decision not to disclose details of the recall, Straw said: "Our motivation throughout has been solely to ensure that some extremely serious allegations are properly investigated and that justice is done.

"No one in this country would want anything other. That is what the authorities remain determined to do."

Venables was released in 2001 on licence with a new identity after serving eight years for the infamous murder of two-year-old James.

He and his friend Robert Thompson were just 10 when they battered the little boy to death in Liverpool.

Venables was recalled to custody last week for breaching his licence terms, which included conditions not to travel to the city or contact his accomplice.

The government's refusal to give any details of the breach has prompted a storm of press speculation about what he did.

Straw said: "I said on Wednesday that I was unable to give further details of the reasons for Jon Venables' return to custody, because it was not in the public interest to do so.

"That view was shared by the police and the Director of Public Prosecutions.

"We all feared that a premature disclosure of information would undermine the integrity of the criminal justice process, including the investigation and potential prosecution of individual(s)."

Fergus (42) only found out about his recall on Tuesday shortly before the news became public.

She disclosed her torment about being informed by a probation officer, telling a reporter: "I threw question after question at her, but she blocked every one.

"My fear was that he'd hurt another child, or any human being."