Ofsted inspectors are helping schools to pass their tests by charging £600 a day

Ofsted inspectors are hiring themselves out for up to £600 a day to advise schools on how to pass its inspections, it was revealed yesterday.

An investigation by the website Exaro found that while the schools' regulator bans its staff inspectors from working as consultants, more than 1,000 contracted inspectors are allowed to sell their services to schools. Some even offer to carry out "mock" inspections, in return for payment.

Schools are under huge pressure to perform well in Ofsted inspections as a poor performance can lead to sanctions and even closure. Reports are also used as a vital guide for parents in choosing where they want their children educated.

Now a range of companies has sprung up to offer bespoke mock Ofsted inspections and advice.

One such firm, Weatheroak Inspections, advertises a "full preparation for inspection" package for £800. It includes "advice and editing of the school's analysis and information which would form the basis of its self-evaluation". It also offers a "one-day MOT" for £400.

Weatheroak's director is Alwyne Jolly, a former head teacher and an Ofsted inspector. The company says in its pitch to schools: "The unique dual experiences gained from work both as headteacher and in Ofsted-related roles gives us the edge in advising you of how to manage your inspection."

Last night Mr Jolly said he had not carried out consultancy work of late. "There has not been a call for it recently," he told Exaro. "I just work as a school inspector now."

Andrew Lagden Education Consultants offers a full-day "pre-inspection briefing" by an Ofsted inspector for £600. The consultancy describes itself as "a team of very experienced education professionals, with current Ofsted experience".

It continues: "The team is headed up by Andrew Lagden, who is a very experienced educational consultant and school inspector in both primary and secondary phases."

No one from Andrew Lagden Education Consultants was available for comment last night.

Angela Kirk, who describes herself as a "lead additional inspector for Ofsted", offers "leadership and management support for head teachers, senior leaders and their schools". She charges £500 for a day's consultancy, such as "discussing and evaluating the quality of teaching and learning to agree the judgements using Ofsted criteria". Yesterday she said: "As an Ofsted inspector, I am not allowed to talk to the media."

Chris McGovern of the Campaign for Real Education pressure group called for Ofsted to ban the practice. "This gives an unfair advantage to schools that have the resources to pay for them," he said. "I would rather it were spent on books and teachers' materials than mock inspections that train schools how to jump through hoops and hit targets – not teach."

An Ofsted spokeswoman said: "Ofsted has a robust policy in place that insists that all inspectors disclose whether there are any conflicts of interest with a school. This ensures an inspector who has provided advice to a school would not be involved in any inspection activity with that school."