The Tories' get-tough approach to youth crime runs the risk of serving up "young flesh" to imprisoned sex offenders, Bloc Québécois Leader Gilles Duceppe said Wednesday.

Wide-ranging crime legislation promised this week by Conservative Leader Stephen Harper would make it easier to condemn 14-year-olds to life in prison.

The Tories would seek to introduce maximum life sentences for first- and second-degree murder and 14-year sentences for youths who commit other violent crimes.

That could be a boon for jailed sex offenders, Duceppe said as he campaigned in Montreal.

"Sending children to prison is sending them to the university of crime," Duceppe said. "If we want to be sure of making them criminals, let's do that.

"And it's young flesh as well. Let's not hide it. We know there is that kind of problem in prison, and sending kids there is terrible."

Duceppe's comment 'extreme, irresponsible': Harper

Harper fired back at Duceppe for the suggestion, saying he had crossed the line and demanded Duceppe retract his comments.

"Instead of debating ideas, Mr. Duceppe said extreme, irresponsible and unacceptable things, things that he himself knows are totally false," Harper said at a rally in Courtenay, B.C.

"We're talking here about tougher sentences, but also sentences for crimes that are very serious such as murder and serious sexual crimes," he said earlier in the day in Vancouver.

"It's obvious that people in Canada, and even in Quebec, think the real sentence for such crimes is not child care but rather sentences that are appropriate, even for young offenders."

But Duceppe got some support on Wednesday from the John Howard Society's executive director, who described the Tory approach as "stupid."

Sexual assault "is what happens in prisons," Craig Jones said in an interview.

"In the United States, there's a whole movement devoted to ending prison rape because sex is an instrument of power in prisons and vulnerable people are preyed upon by more powerful people."

Jones said there would be very little chance of rehabilitating young offenders under the Conservatives'  approach.

"Putting 14-year-olds in a population of federally sentenced prisoners is essentially throwing them away," said Jones, whose organization helps prisoners and young offenders.

Panders to fears: Jones

Jones blasted Harper's tough-on-crime agenda as being "from the book of retribution and vengeance."

"It's an attempt to pander to the fears of people who really don't know very much about the criminal justice system, who sort of subscribe to the notion of an eye for an eye and a tooth for a tooth."

Jones stressed he was not trying to excuse the fact some young people commit violent crimes, but he said the issue must be put in context.

"We need to get smart on crime, rather than just tough, because the evidence shows that getting tough on crime amounts to getting stupid on crime and throwing away lives that can be rehabilitated."

Liberal Leader Stéphane Dion said judges are the experts and therefore should be able to exercise their discretion in sentencing young people.

"These individuals will be exposed to much more serious criminals that will influence them for the rest of their life," Dion said during a rally in Winnipeg.

"We know in the United States it did not work. It's why judges don't want to do that. It's not because they are soft or they don't understand, because they understand more than Stephen Harper."