Ofsted is being used as a “political tool” by ministers, Labour’s education spokesman claimed last night, as he accused the watchdog of forcing inspectors to fail schools in order to trigger mandatory conversion to academy status.

Tristram Hunt, the shadow education secretary, made the controversial statement during the TES political hustings in London on Wednesday evening, which also featured education secretary Nicky Morgan and the Liberal Democrat schools minister David Laws.

Responding to a question from the audience, Mr Hunt said that, should his party come to power after May’s general election, he would ensure Ofsted would remain “truly” independent of government, claiming schools were being failed at the behest of the Department for Education.

“I want to see stability in the inspectorate, quality of inspectors and also crucially not to have Ofsted used as a political tool,” Mr Hunt said. “I want Ofsted to return as an independent inspectorate. So whether you’ve got performance-related pay or not it should not be a judgement on the quality of that school.

“And I have had Ofsted inspectors tell me that they have come under pressure from the DfE to fail a school so it could become an academy.”

Ms Morgan dismissed the claims that ministers have interfered with Ofsted’s inspections, adding that her opposite number had “obviously never met” Ofsted’s chief inspector Sir Michael Wilshaw. “He is the most independently minded person I’ve met in education,” she added.

Ofsted said it took the accusations very seriously and would like to see any evidence of wrongdoing.

An Ofsted spokesperson said: “Ofsted has long valued its independence and ability to report without fear or favour. These are very serious allegations, which we simply do not recognise. If anyone has evidence that any inspector has ever come under political pressure to fail a school then we would urge them to come forward with this as a matter of urgency.”

It is not the first time doubts have appeared over Ofsted’s impartiality, with reports last year that so-called academy brokers working on behalf of the DfE were using “heavy-handed” tactics to push academisation.

Headteachers told a newspaper that the brokers were calling up schools even before they had received their Ofsted inspection reports in order to pressure them into converting to academy status.

UPDATE:

Ms Morgan has written a letter to her opposite number accusing him of making “deliberate smears” and demanding he withdraw his remarks made at the TES political hustings.

The education secretary writes that the accusations made about Ofsted being pressurised by the DfE to give “negative” judgements as “categorically untrue”, and she adds that it risks “undermining confidence” in the inspectorate.

The Cabinet member also called for Mr Hunt to apologise to Ofsted’s chief inspector Sir Michael Wilshaw.

“I am of course now resigned to your attempts to undermine the significant progress that our schools and teachers have made over the past five years to improve young people’s life chances,” she writes.

“But what I will not tolerate is a deliberate attempt to smear my department and question Ofsted’s independence, something which is simply not befitting of a someone seeking to hold the office of education secretary.”

TO WATCH THE DEBATE CLICK HERE