British teacher shortages are at the worst level for 36 years, the chief education inspector, Mr Mike Tomlinson, said yesterday.
Headteachers, parents and opposition politicians urged ministers to take his views seriously and act to stem the exodus of young teachers from the profession, which the Ofsted chief warned had reached 40 per cent.
But the government hit back, saying there were more staff in English schools than at any time since 1984 and that three-quarters of new recruits were still in the job after their third year.
In an interview with the Guardian, Mr Tomlinson, a teacher since 1965, said: "I think over my period of time in education this is about the third major cycle of this sort. "I do think this is probably the worst of the three ... more widespread."
It was particularly important to ensure young teachers did not leave disillusioned soon after qualifying, he said. "Our data suggests that ... through to three years teaching we lose up to 40 per cent - that is the core issue."
He urged the government to do more to retain those who were on salaries that offered them little hope of getting on the property ladder.
The Department for Education and Skills rejected his assertion that four young teachers in 10 left within three years.