The number of schools classified as failing or suffering serious weaknesses has shot up by a third since the start of a new inspection regime this term. Teaching can be rated as unacceptable even if most lessons are satisfactory under the new framework.
And the Office for Standards in Education revealed this week that the number of schools put into special measures in September and October was 46, around 35 per cent more than for the same period last year.
In the same two months 39 schools were found to have serious weaknesses, an increase of around 30 per cent.
The figures were disclosed when David Bell, the chief schools' inspector, was questioned by MPs from the Commons education select committee.
Mr Bell was asked whether he felt the increase in schools failed by inspectors was linked to the new guidance to inspectors on judging satisfactory teaching, revealed by The TES earlier this year.
He said it was too early to draw conclusions about the figures and that he would be more concerned if those for the whole year showed a rise in schools in special measures or serious weaknesses.
"Headteachers say that the issue with the new framework is not the satisfactoryunsatisfactory borderline, but the clearer criteria for distinguishing good from satisfactory teaching," he said.
Mr Bell said he was disappointed that the problems which led schools to be placed in special measures were similar to those from five and 10 years ago.
After the committee, he added: "It is the familiar litany of problems: teaching is not very good, leadership and management is poor, the governors are not holding the school to account. A whole range of things have to be wrong with a school before it can be placed in special measures."
MPs criticised Ofsted for its inspection in 1996 of St John Rigby college in West Wickham, Kent, where inspectors reported the school had strong management, a clear ethos and good financial management.
Its then headteacher Colleen McCabe was imprisoned this year after it was revealed that she had embezzled pound;500,000 and left pupils in unheated and dirty classrooms.
Paul Holmes, Liberal Democrat MP for Chesterfield, said: "The head was not just a thief, she was a bully. How can we be sure Ofsted doesn't produce reports like that, that are not worth the paper they were printed on?"
Questions were also raised about whether Ofsted was worth pound;200 million of taxpayers' money each year. Robert Green, its director of strategy and resources, said the watchdog would shortly be holding a major research exercise into its own effectiveness and that first details would be published in Easter.
However, the plan received a sceptical response from David Chaytor, Labour MP for Bury North. "That's rather like police investigating complaints against the police," he said