Up to 20,000 families will be given intensive support to help get their wayward children back on track as part of a 100 million pound government plan to curb youth crime, the Home Office has announced.

The widely trailed programme was unveiled amid mounting concern over knife crime following a spate of stabbing deaths in London.

Opposition parties have accused the government of delivering a "half-baked" scheme after Home Secretary Jacqui Smith gave early details of plans to force those caught with knives to visit hospitals to see stabbing victims for themselves.

But Children's Commissioner for England Al Aynsley-Green said the programme was "a courageous initiative that sets out measured, thoughtful proposals and a long-term plan."

By 2010, the government wants to have extended its Family Intervention Project to 20,000 of the most troubled families, offering support but also threatening sanctions such as eviction from social housing for those not cooperating.

In all, it hopes to reach 110,000 families where children are at risk of falling into crime.

"Increasingly we are able to identify these young people early and intervene to address the root causes of their behaviour, including supporting and challenging their parents in meeting their responsibilities," Smith said.

The Youth Crime Action Plan aims by 2020 to cut by a fifth the 100,000 children aged 10 to 17 who enter the criminal justice system each year.

In so doing it also hopes to substantially reduce the numbers of young victims - 20 teenagers have died a violent death so far this year in London as increasing numbers of youths carry knives.

Other provisions include:

- Greater use of police enforcement such as evening curfews

- Stricter sentencing

- Making permanent exclusion from school an automatic trigger for wider assessment of needs

- improving support for witnesses when they attend court

- a new duty on local authorities to help educate young offenders in custody

"The vast majority of young people are not involved in crime but we must to be tough on the few young people who are and reduce the harm they cause," said Children's Secretary Ed Balls.

"By targeting families and spotting the problems where children and young people are getting out of control we can intervene and transform their lives."