“The Government is speaking with a forked tongue,” said Nigel de Gruchy of the National Association of Schoolmasters Union of Women Teachers. “On the one hand the report emphasises the need for discipline, unambiguous rules and a clear hierarchy of sanctions, but many of the recommendations, if implemented, will seriously undermine the authority of teachers.”

The plans - published this week in the Social Exclusion Unit’s report - have been welcomed by police, social workers and academics for promoting prevention rather than punishment. And the National Children’s Bureau says they will help protect children’s rights.

“Maintaining children in school is a responsibility shared by different agencies,” said Ruth Sinclair, the bureau’s research director. “We hope the report will set a trend for multi-agency work to benefit all children, but particularly those most likely to miss out on their education.”

The proposal to give the police powers to pick up truants was controversial. Police organisations said they welcomed the clarification of their role, but social workers warned that children could become confused about how to react to strangers in the street.

“It goes against the advice we give to young people,” said Lawrence Warburton of the National Association of Social Workers in Education. “There will need to be very good public awareness that the scheme is only operated by uniformed officers as part of specified projects so you can’t have people pretending to be undercover police and trying to force youngsters into their cars.”

The police also hope the action to reduce school exclusions would help reduce youth crime.

But this link was condemned by Mr de Gruchy. “Many youngsters displaying serious behavioural problems at school are already in trouble with authority, including the police, before they are permanently excluded.

“Proposals to outlaw exclusions for certain behaviour is an outrageous attempt to tie the hands of teachers facing an uphill battle over indiscipline in schools.”

Peter Smith, general secretary of the Association of Teachers and Lecturers, disagreed. “The Government is perfectly right in thinking that far too many children are not in school when they should be. There is evidence that a large percentage of them are making a nuisance of themselves, if not actually committing crimes.

“But normal school is not the answer for all of these children: some will need special provision.”

Doug McAvoy of the National Union of Teachers welcomed the recognition of parental responsibility, but said more money was needed to help schools with children with behavioural problems.