Contempt proceedings are to be brought against a number of people who posted photos claiming to show James Bulger killers Jon Venables or Robert Thompson on the internet, the Attorney General said.
Venables was 10 when he and classmate Thompson abducted and murdered two-year-old James in Liverpool in February 1993.
Images recently appeared on the social network site Twitter claiming to show an adult Venables, who was released from jail on licence with a new identity in 2001.
The Attorney General said court papers will be served shortly to bring contempt proceedings against those who posted the pictures, which have since been taken down.
Dame Elizabeth Butler-Sloss, of the High Court Family Division, made an unprecedented court order banning publication of any information which could lead to the revelation of their new identities.
A statement from the Attorney General's Office said: "The terms of the order mean that if a picture claims to be of Venables or Thompson, even if it is not actually them, there will be a breach of the order.
"Providing details of the new identities of Venables and Thompson or their whereabouts is also prohibited - this order applies to material which is on the internet.
"There are many different images circulating online claiming to be of Venables or Thompson - potentially innocent individuals may be wrongly identified as being one of the two men and placed in danger.
"The order, and its enforcement, is therefore intended to protect not only Venables and Thompson but also those members of the public who have been incorrectly identified as being one of the two men."
Breaches of the order may be a contempt of court punishable by a jail sentence or fine, the statement said.