Council leaders have called for an independent review of Ofsted following a series of “leaks and U-turns” that they said had undermined the watchdog’s credibility.

The Local Government Association (LGA) pointed to Ofsted’s “habit of re-inspecting schools when they hit the headlines”, generally leading to them being downgraded from good or outstanding to inadequate.

Town halls highlighted the recent Trojan Horse scandal in Birmingham, where the Ofsted ratings of five schools were downgraded, in some cases after less than a year. Councils also raised the fact that the judgement of Haringey’s children’s services was revised downwards after the Baby P scandal broke.

The trend raised questions over the validity of the inspectorate’s judgements, the LGA said.

Councillor David Simmonds, chairman of the LGA’s Children and Young People Board, said: “Too many controversies have threatened Ofsted’s independence and credibility. Mums and dads put their trust in Ofsted’s ratings when they pick a school for their children and its inspections can have implications for the most vulnerable children in our care.

“Councils, communities and parents need to know Ofsted and the chief inspector are independent and free from political influence, and we need an independent review to discover what has gone wrong and restore faith in what is fast becoming a media-driven organisation.”

The call for an investigation comes on the same day as chief inspector Sir Michael Wilshaw gave a speech to the National Children and Adult Services Conference.

In a statement in response to the LGA, Ofsted said it was “simply incorrect to suggest our inspection judgements are influenced by anything other than the evidence we find”.

The statement continues: “We know that previously high-performing institutions can deteriorate rapidly when they suffer staff turbulence or a sudden change in leadership.”

It adds that nearly eight in 10 schools are judged to be good or better, and that hundreds of thousands of children are benefiting from a better education because of the “challenge” the body offers.

“But we also know that when you challenge the system to do better, it will push back,” the statement says. “Of course, Ofsted is not perfect and we have been open about where we need to improve our own performance. We are currently consulting on radical changes to the way we inspect schools and colleges from next September as well as taking steps to bring all education inspectors in-house.”

Teaching union the NUT said it would support an investigation, but added that “nothing short of Ofsted’s abolition and replacement” would be a sufficient outcome.

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Ofsted should no longer judge quality of teaching, says former Gove aide - May 2014