Proposals for mandatory jail sentences for carrying a knife could make young people more likely to commit crime, Liberal Democrat justice minister Simon Hughes has warned.
The issue of knife crime has split the coalition, as Deputy Prime Minister Nick Clegg said he would block proposals from Justice Secretary Chris Grayling for an automatic jail sentence for anyone caught in possession of a knife on two occasions.
Labour leader Ed Miliband has said he is "sympathetic" to moves to introduce tougher knife crime sentences, and the proposal has won the backing of Metropolitan Police Commissioner Sir Bernard Hogan-Howe and London Mayor Boris Johnson.
Lord Chief Justice Lord Thomas, the most senior judge in England and Wales, has also called for an urgent review of sentencing for youths carrying knives, saying it was a "major problem" among 12 to 14-year-olds.
MPs will have a chance to debate the proposal on Monday, when an amendment to the Criminal Justice and Courts Bill tabled by Conservative backbencher Nick de Bois comes before the Commons.
Mr Hughes denied that the Lib Dem opposition to mandatory punishments was a sign of "weakness", insisting that removing judges' discretion on sentencing was not the most effective way of tackling knife crime.
And he warned that the proposals could lead to younger teenagers ending up in jail after being pressurised by older youngsters to carry knives for them.
"Sometimes youngsters in particular will be carrying a knife only very briefly when it's been given to them either by an older brother or sister, perhaps just before an event happens and the police come and it's the younger teenager who has the knife," Mr Hughes told BBC Radio 4's Today programme. "Or they might be out with a group of people and suddenly pressure is put on somebody to take a knife - they didn't go out with a knife, they were handed the knife.
"They find themselves in a position where they can't do anything about the fact that suddenly they are under pressure and given a knife and caught with it.
"The question then is do you allow the judge, in all the circumstances, to make a decision that this is a very serious offence and they should go to prison for a certain time - which the judge has complete authority to do - or do you allow the judge, as we have traditionally done in England, to decide what the sentence should be?
"There's a high maximum sentence, but the question is should there be an absolute minimum that applies in all circumstances?"
Mr Hughes warned that sending youngsters to jail can direct them into a life of crime.
He said: "If you send somebody to jail, possibly for the first time, the likelihood is and the experience often is that they come out, having met the sort of people they are in prison with, more likely to commit an offence, more used to working with and getting on to have the sort of teaching from the lifestyle of people who are in prison with them.
"The whole transforming rehabilitation policy of the Government is to try to not have people being sent to prison for short periods because we know how often they are the sort of people who, when they come out, go back to prison again.
"We want to be tough on people carrying knives and carrying guns. There's no weakness about this. The question is what is effective.
"We believe that to give the judge the power to give a very tough sentence but, in circumstances where it justifies it, to have the flexibility to say 'I don't think in this circumstance that you going to prison is the right answer' is the most effective remedy and most in the interest of the public."