The Ministry of Justice announced Jon Venables, 27, was detained last week, The Times of London reported Wednesday.
Venables and Robert Thompson, also 10 at the time, were given life sentences in 1993 for abducting 2-year-old James Bulger from a shopping center in Bootle near Liverpool and killing him. They were held in separate facilities until their 18th birthdays and then released on lifetime parole with new identities.
The ministry did not say how Venables breached the conditions of his release, which include staying away from Thompson, the dead boy's family and the Liverpool area, and avoiding drug use and any new crimes. Venables faces a parole hearing where more information could become public.
Home Secretary Jack Straw said he believed the public should be told what Venables had done but said he was not free to release the information, The Daily Telegraph reported.
Denise Fergus, James Bulger's mother, sent out a Twitter alert Tuesday: "Would like to let everyone know Jon Venables is where he belongs tonight behind bars. Is this my son's justice?"