James Bulger's mother called for the Children's Commissioner to be sacked for "twisted and insensitive" comments about the murder of her two-year-old son.
Denise Fergus spoke out after Dr Maggie Atkinson said his killers should never have been prosecuted because they were too young to understand the full consequences of their actions.
The Ministry of Justice yesterday ruled out Dr Atkinson's proposal to raise the age of criminal responsibility from 10 to 12 years, saying children aged 10 and over did know the difference between "bad behaviour and serious wrongdoing".
Dr Atkinson described the killing as "exceptionally unpleasant" but said it was wrong that Robert Thompson and Jon Venables, who were 10 in 1993 when they were charged with the boy's murder, were tried in an adult court.
Mrs Fergus told reporters: "This woman owes James and me an apology for her twisted and insensitive comments. Then she should resign or be sacked.
"To say that his killers should not have been tried in an adult court is stupid. They committed an adult crime - a cold-blooded murder that was planned and premeditated and they were tried accordingly."
She added: "It is a shock to people like Dr Atkinson that children can be truly evil by 10. But it is a fact and I fear there will be more of them and we need laws to be tightened up so we can deal with them."
Dr Atkinson said children under the age of 12 should not be prosecuted for any crime.
But the Ministry of Justice responded by saying: "We believe that children aged 10 and over can differentiate between bad behaviour and serious wrongdoing.
"We do not intend to raise the age of criminal responsibility.
"It is not in the interests of justice, of victims, or the young people themselves, to prevent serious offending being challenged."
The MoJ said custody for under-18s was "always a last resort" and only 3% of young offenders who are convicted receive a custodial sentence.
Mrs Fergus met Justice Secretary Jack Straw earlier this week to discuss the return to custody of Venables.
Mr Straw has repeatedly refused to confirm the details of why Venables was returned to custody and has said only that he faces "very serious allegations".
Criminal barrister Felicity Gerry, a specialist in prosecuting and defending child offenders, said current laws already required Crown Prosecution Service lawyers to first decide whether a child understood what they did was wrong.
She said: "My view is that there is no need to change the age of criminal responsibility providing that prosecutors are applying the proper tests in deciding whether or not to prosecute.
"The current situation is that the prosecution of any particular child would depend on the specific circumstances in which the alleged crime was committed and whether it is in the public interest."
She said the burden was on the prosecutor to decide not just whether there was sufficient evidence for prosecution, but also to ask whether the child was fit to be tried, whether they understood what they did was wrong, and to look at the nature of the offence.
Until the late 1990s the law required proof that a child knew what they did was seriously wrong before a prosecution could take place.
Dr Atkinson told The Times yesterday: "The age of criminal responsibility in this country is 10 - that's too low, it should certainly be moved up to 12; in some European countries it is 14.
"The 'we are too worried about the parents issue' is something that runs like a thread through a number of cases. My constant song is 'listen to the children and young people'."
She said the James Bulger killing was a "dreadful thing", and Venables and Thompson, who were 10 in 1993 when they were charged with the boy's murder, needed to be in a contained environment like a youth justice facility and given programmes to help them turn their lives around.
Seeking to clarify her views later, she said it was right for children like James Bulger's killers who commit terrible crimes to be held in secure settings.
She said: "Children who carry out such atrocities and other serious offences need to understand the severity of their actions.
"They should undertake intense programmes appropriate to their age in secure facilities where they are helped to make positive and lasting changes to their behaviour."
But Ms Gerry said this kind of rehabilitation was already being applied to children, adding: "You can't hold people securely unless you have proved they have done something wrong so you would have to have some form of litigation."
Shadow justice secretary Dominic Grieve said: "Seeing that the Ministry of Justice has always previously said that the age of criminal responsibility should not be raised, this intervention is sending out mixed messages.
"Changing the age of criminal responsibility is not the answer. We need fundamental reform to address the causes of offending by children, including family breakdown, poverty, gang culture and school discipline."
Juliet Lyon, director of the Prison Reform Trust, said: "While we cannot expect justice on the hoof from jumpy politicians, after the general election it would be wise to review the age of criminal responsibility, taking into account standards set by the UN Convention and international comparisons."Reuse content