Plans to give young people mandatory custodial sentences for knife crime has been slammed by urban youth work charity XLP.

Founder Patrick Regan OBE says the government is spending too much on the consequences of knife crime, and too little on preventative measures.

"The facts show that we are spending far more money on locking our young people up and dealing with the consequences than in attempting to work with young people before they get to this point," he said in a statement.

"Early intervention is not only beneficial to our society as a whole, enabling young people to contribute positively to their communities, but it actually saves the government money."

Regan said that while "no one should get off scot-free for breaking the law," the issues leading young people to the point of committing offences must be the primary concern.

"From nearly 20 years of experience working with some of the most hard to reach young people, we know only too well the tragic consequences of young people carrying knives," he said.

"More than most, we have seen the pain and suffering it can bring. Yet, more than most we also know the reasons that many of these young people are carrying knives in the first place and they vary massively."

XLP is contesting the Criminal Justice and Courts bill which is to progress through its third reading in the House of Commons next Monday. It contains an amendment to introduce two year sentences for a second knife offence, six months for young people, regardless of the circumstances, and if passed on November 10 will become law.

The charity believes that this amendment will have a disproportionate social and financial cost, and is calling for investment into mentoring initiatives instead.

Mentoring a young person costs £4,000 a year, while to send them to a Young Offenders Institute, Secure Training Centre or Secure Children's Home cost upwards of £65,000 per place.

Additionally, reoffending rates among young people who attend these institutes are high, at over 70 per cent.

London MP and Minister of State at the Ministry of Justice, Simon Hughes, told the Independent: "For a large number, prison hasn't worked and isn't working," and said jail sentences are often no more than "sticking-plaster solutions".

"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," he said in May.

"We want to be tough on people carrying knives and carrying guns. There's no weakness about this. The question is what is effective."

Hughes said it is in the public's best interests for judges to have flexibility in their sentencing; a comment backed up by Lib Dem MP for Cambridge Julian Huppert, who argued in June that the amendment could encourage senior gang members to force vulnerable, younger members to carry their knives for them.

"The question I think this House has to look at is whether we should be trying to take the thing that sounds the toughest or whether we should try to do the things that actually work," he told the Commons.

However, Labour's shadow justice minister Andy Slaughter spoke in favour of the bill. He described knife crime as one of the "most serious and intractable criminal justice issues, one that leaves irrevocable damage in its wake".

"Prevention is better than cure, but it is important the message goes out from this House that carrying a knife without good reason is unacceptable," he said.