The attorney general has launched an investigation after photographs purporting to show killer Jon Venables were allegedly posted on the internet.
Venables was 10 when he and classmate Robert Thompson abducted and murdered James Bulger, two, in February 1993. The pair were jailed for life but released on licence with new identities in 2001.
Dame Elizabeth Butler-Sloss, of the high court family division, made an unprecedented court order banning publication of any information that could lead to the revelation of their new identities.
Venables, now 30, had his parole revoked in 2010 and was jailed for two years after admitting downloading and distributing indecent images of children.
The images, which appeared on Twitter, claimed to show an adult Venables posing with friends. The posts have been removed.
A spokesman for the attorney general's office said: "The AGO has been alerted to a possible contempt of court. We are liaising with the Ministry of Justice and others to establish the facts.
"We can neither confirm nor deny whether the pictures in question are of Jon Venables. It should be noted there is a worldwide injunction in place which prevents the publication of any images or information purporting to identify anyone as Jon Venables."
Bulger's mother, Denise Fergus, has made no comment about the alleged breach. However, she remains opposed to the injunction, fearing it could lead to innocent men being accused.
Venables and Thompson abducted James from the Strand shopping centre in Bootle, Merseyside, before torturing and killing him. His body was found two days later.