Michael Gove's decision to appoint a former anti-terror chief to investigate allegations of a hardline Islamist takeover plot at a number of Birmingham schools is drawing increasingly heavy criticism.

The Education Secretary earlier announced that Peter Clarke, who served as head of the Metropolitan Police's counter-terrorism unit, is to become Education Commissioner, with responsibility to investigate the allegations.

But the move was swiftly attacked, with one top police office saying it was a "desperately unfortunate appointment" and suggesting that Mr Clarke's previous experience - which includes leading the investigation into the July 7 bombings in London - would inevitably lead to people drawing "unwarranted conclusions".

Mr Clarke has been tasked by Mr Gove with reviewing the evidence in connection with the Birmingham allegations.

His role will be to conduct an investigation to fully understand the situation and work with Birmingham City Council to "analyse evidence of extremist infiltration in both academies and council-run schools", the Department for Education (DfE) said.

It added that Mr Clarke has substantial experience in leading high-level investigations and his appointment means that the allegations can be examined in a "professional and dispassionate manner".

But West Midlands Chief Constable Chris Sims said : "This is a desperately unfortunate appointment. Peter Clarke has many qualities but people will inevitably draw unwarranted conclusions from his former role as national co-ordinator for counter terrorism.

"I am a strong supporter of open and inclusive education for all children in Birmingham and across the West Midlands and am committed to the process adopted by Birmingham City Council with educational and social inclusion at its heart."

The West Midlands' elected Police and Crime Commissioner for the West Midlands, Labour's Bob Jones, said he shared Mr Sims' concerns.

"This appointment gives the clear impression that the issues around Trojan Horse are predominantly around counter-terrorism issues," he said.

"My main concern is that the Secretary of State is attempting to divert attention away from the governance and diversity issues that might be embarrassing to his policies and approach to school governance.

"This would be at the expense of sending a completely inappropriate message to our local community."

Mr Jones added: "I have every admiration for Peter in his previous role, but having had personal experience as an ex-chair of primary, secondary and college governors and having led on the Education Authority, I feel he lacks the relevant experience in educational governance issues that are key to this investigation."

Mr Gove said that he was "extremely concerned" about the allegations that have been made, and that while Ofsted is inspecting a number of schools of concern, more action was needed.

" These allegations need either to be substantiated and firm action taken, or to be shown to be baseless," he said.

"We cannot allow uncertainty for parents or pupils to persist.

"That is why I am appointing a Commissioner to oversee this work. Peter Clarke brings a wealth of relevant skills and experience, and is very well placed to lead a fair and thorough assessment of the evidence, and report back to me. We expect he will work closely with Birmingham City Council.

"No pupils should be exposed to extremist views or radicalisation while at school. I have tasked Peter Clarke with getting to the bottom of these allegations, so schools in Birmingham can continue the excellent progress that so many have been making."

Mr Clarke's appointment comes the day after it was disclosed that 25 schools are now under investigation over the alleged hardline Muslim plot to force out governors and headteachers.

Birmingham City Council has already announced it is appointing a new chief adviser, Ian Kershaw, managing director of Northern Education, to directly handle at least 200 complaints received in relation to the Operation Trojan Horse allegations focusing on schools in the city. It is also setting up a review group.

The council's investigation, running in parallel to the DfE's separate inquiry, is due to initially report back in May.

Mr Clarke is due to report back with his findings in the summer. His remit will cover both local council-run schools and academies.

Concerns over how some of the city's 430 schools were being run first emerged when an anonymous letter known as Operation Trojan Horse was leaked, claiming a small but radical group of Muslims were pursuing their own agenda in the classrooms, with uncooperative headteachers and governors forced out.

The unsigned and undated document also claimed to have caused "a great amount of organised disruption" in the city, crediting the plan with forcing a change of leadership at four schools.

Since the letter came to light, anonymous whistle-blowers have claimed that boys and girls were segregated in classrooms and assemblies, sex education was banned, non-Muslim staff bullied, and in one case it was alleged that the teachings of a firebrand al Qaida-linked Muslim preacher were praised to pupils.

Birmingham City Council leader Sir Albert Bore has said that West Midlands Police is still looking into the authorship of the document.

The allegations detailed in the Trojan Horse letter focus on the Park View Educational Trust, which runs three schools in the city - all of which have been subjected to snap Ofsted inspections in recent weeks.

Among further claims which have since come to light, one former anonymous staff member at Park View Academy in Alum Rock alleged a colleague had in an assembly praised the firebrand al-Qaida-linked Muslim cleric Anwar al-Awlaki - he was killed by a US drone strike in Yemen in 2011.

The school trustees have firmly denied all the claims, branding the allegations "a witch-hunt", while pointing to very good academic results among its pupils.