The mother of murdered child James Bulger said that the Parole Board had made the “wrong decision” by moving to release one of her son's killers.
Denise Fergus said that Jon Venables had shown he was still "a danger to himself and to the public".
She was speaking after receiving a call from the Probation Service telling her that Venables, now 30, had been cleared for release for a second time.
He returned to jail in 2010 after his parole was revoked, following the discovery that he had accessed indecent images of children. Venables admitted the offence and was jailed for a further two years.
He had previously been sentenced for life alongside Robert Thompson following the 1993 murder of two-year-old James, who was beaten to death on a railway line after being taken by Venables and Thompson, then both aged 10, from Bootle Strand shopping centre in Merseyside.
Both were released in 2001 and given new identities, with a legal ruling ordering that new photographs of them should not be published. Thompson has not been heard of since his release. Earlier this year, Mrs Fergus, and James's father, Ralph, both addressed Venables's parole hearing, calling for him to stay in prison.
"I've been fighting for justice for James for 20 years now and I will continue to do so. The Parole Board have made the wrong decision," Mrs Fergus added.
She had earlier broken the news of the Parole Board's decision on Twitter, adding the message: "Just don't believe what I've got to go through. Again."
When he was re-arrested in 2010, it was claimed Venables had become a heavy drinker and had, in a paranoid state, revealed his past to friends.
A Ministry of Justice spokesman said: "The re-release of life-licensed offenders is directed by the independent Parole Board once they are satisfied they can be safely managed in the community. They may be recalled to prison at any time for breaching their licence conditions."
A spokesman for the Parole Board confirmed Venables would be released. It is not known when this will be.