In a get-tough speech a long way from previous teacher friendly offerings, the Conservative leader warned that education was still suffering from a 1960s hangover. He repeated the Tories 2005 election pledge of full anonymity for teachers until any allegations against them were dealt with.

But instead talking of the need to trust the profession Mr Cameron said it was time for the state sector to admit it was “doing a bad job” with “tough kids”. “Schools should be places where teachers teach and children learn not holding centres for kids no matter how badly they behave,” he said.

“Most of all, they should be places where the kids respect and even fear the teachers, not the other way around.”

The speech, made against a backdrop of internal Tory criticism, backfired as the Government said Mr Cameron was unable to discipline his own party and a teachers’ leader accused him of talking nonsense.

Mary Bousted, Association of Teachers and Lecturers general secretary, said: “How does he square the circle of providing support for the most vulnerable children and then saying they should be scared stiff in school?”

Mr Cameron called for less reliance on pupil referral units which were “the weakest link” in the system. Instead independent charities should have a right to supply education to pupils excluded from school. “It’s time for the state sector to say that when it comes to these children, we’re doing a bad job and you’re doing a great job we want to trust you with more of the resources, more responsibility, longer contracts and more freedom,” he said. Kevin Brennan, schools minister, admitted to The TES that leadership in the units needed strengthening.

Mike Royal, director of the Lighthouse group, a Bradford based charity cited by Mr Cameron for its work with excluded pupils, declined to echo the Conservative leader’s criticisms of the state system. But he said he was frustrated that money pumped into schools for disaffected pupils was often submerged in general budgets and not available when needed.

Mr Cameron said that under Labour too many children were out of control and on a conveyor belt to prison. “Instead of going from key stage 3 to GCSE to A level, too many children are going from Asbo to Young Offenders’ Institutes to Her Majesty’s Prison,” he said.

His solutions included previous Conservative policy such as enforceable home school contracts and scrapping independent exclusion appeals panels.

But Peter Jenkins, chairman of a Sheffield appeals panel, defended the panels’ role at the Professional Association of Teachers conference in Harrogate saying they were a check against the sometimes rash decisions of dominant heads.