Media playback is unsupported on your device Media caption Ofsted chief Sir Michael Wilshaw told the BBC's Newsnight programme that he had called for unannounced inspections in schools two years ago

Concerns about a takeover of some Birmingham schools by people with a hard-line Islamic agenda have proved the case for no-notice Ofsted inspections, Sir Michael Wilshaw says.

The chief inspector of England's schools added he had set out plans for unannounced inspections in 2012.

But he had decided instead on a half-day notice period after representations from "head teachers and others".

On Monday he had said the education secretary had halted snap inspections.

Now, amid concerns about the "Trojan Horse" claims, Michael Gove has asked Ofsted to introduce snap inspections.

Schools 'as they normally are'

In a statement issued on Tuesday afternoon, Sir Michael said: "When I first became chief inspector in early 2012, I set out plans to introduce no-notice inspections for all schools as part of a wider package of reforms to improve the inspection system.

Image caption Ofsted chief Sir Michael Wilshaw says inspectors will see schools "as they normally are"

"As a result of representations I received from head teachers and others during the consultation, I decided to move instead from two days' notice to much shorter half-day notice inspections from September 2012.

"Events of recent weeks have served to reinforce my original view that no-notice inspections for all schools are the best way to make sure that, for every school we visit, inspectors see schools as they normally are.

"I recognise that the secretary of state's commitment to this principle is also long standing.

"The prime minister and the secretary of state have asked me to look at the practicalities of moving to a system of routine no-notice inspections, and today I can confirm my intention to take this issue forward as part of our wider review of the future of school inspection, which I have already set in train."

'Important reform'

The Department for Education also issued a statement on Tuesday, saying: "The chief inspector confirmed that the education secretary did not ask Ofsted to halt its plans for no-notice inspections in 2012.

Image caption Mr Gove denied blocking no-notice inspections two years ago

"Ofsted took the decision after considering the response to their consultation.

"The secretary of state yesterday commissioned the chief inspector to examine the practicalities of extending the use of no-notice inspections, so that any school can expect an unannounced visit.

"Both look forward to working together to implementing this important reform."

BBC political correspondent Norman Smith said sources in the DfE say Sir Michael and Mr Gove discussed the idea two years ago and jointly agreed not to proceed with snap inspections because of opposition from some of the teaching unions.

But the sources also stressed the Ofsted chief already had the power to introduce snap inspections but had chosen not to, our correspondent said, and this was the reason Mr Gove had now written to him urging him to introduce the checks.

'Serious failure'

Deputy Prime Minister Nick Clegg told BBC Radio 4's Today programme no-notice inspections had an important part to play in cases where the leadership of a school had changed suddenly.

Mr Clegg said ministers might have to look more widely at what is taught in schools, including academies, which have a high degree of autonomy.

"Maybe one of the things that we need to think about is how do we make sure that... a core curriculum, not a great sprawling one, is taught in all schools in our country regardless of the nameplate at the school gate," he said.

When Sir Michael delivered his findings on claims of hard-line Muslim takeovers, he said "a culture of fear and intimidation has taken grip".

Media playback is unsupported on your device Media caption Reaction to Ofsted chief Sir Michael Wilshaw's findings

The Ofsted chief said there was evidence of an "organised campaign to target certain schools".

Ofsted carried out inspections of 21 schools, following claims in an anonymous letter that hard-line Muslims were trying to impose their views on a group of schools in Birmingham.

Five "Trojan Horse" schools - including three academies from the Park View Educational Trust - are being placed in special measures. A sixth school is also labelled inadequate for its poor educational standards.

Ofsted says 12 schools will need to improve - three others emerged with praise rather than criticism.

Mr Gove told the House of Commons the funding agreements for these academies will now be terminated - with new sponsors lined up to take them over.

Local authority schools will have their governing bodies replaced.

Mr Gove says that he wants all schools to "actively promote British values", such as democracy, individual liberty, mutual respect and tolerance of those with different faiths.

Speaking to MPs, Mr Gove also called for teachers who invited extremist speakers into a school to be banned.

He also promised a review of how the Department for Education had responded to previous warnings - after claims from school leaders that they had raised concerns with ministers in 2010.

Labour's Tristram Hunt said that "warring egos" had left the government's education policy in "disarray".

'No extremism'

David Hughes, vice-chairman of the Park View Education Trust, said there was no extremism and attacked the "knee-jerk reaction of politicians".

"The Ofsted reports found absolutely no evidence of this because this is categorically not what is happening at our schools."

Head teachers' leader Brian Lightman said: "Extremism of any kind has no place in education."

But he warned that the "constant cycle of leaks and accusations over the last few weeks will have been demoralising and damaging for students and staff caught up in this ongoing drama".