Ofsted has been accused of putting pressure on schools to base teachers’ pay on how their students perform in exams.

A right-leaning think-tank with close links to education secretary Michael Gove has claimed that Ofsted is “misinterpreting” official Department for Education (DfE) guidance, which recommends that schools base performance-related pay decisions on a range of factors.

Jonathan Simons, head of education at Policy Exchange, told a seminar held in London that Ofsted was “wrong” and was effectively encouraging schools to link pay with student attainment, rather than incorporating other measures of teacher performance.

The DfE’s guidance suggests schools could take into account teachers’ “impact on pupil progress”, but also suggests their “impact on wider outcomes for pupils”, improved teaching practice, teamwork and “wider contribution to the work of the school” could be considered.

But at the Westminster Education Forum’s seminar on performance-related pay earlier this week, Mr Simons was outspoken in his criticism of how the guidance is being interpreted by inspectors.

“I don’t know how to say this any more explicitly than: Ofsted are wrong,” he told the audience.

“The DfE guidance could not be more explicit - it says there are five things which schools can choose to base performance-based progression on… If Ofsted are misinterpreting DfE guidance and prescribing to schools that which is theirs [to decide] autonomously, they are wrong and should be challenged during an inspection, shown the guidance and told they are wrong.”

The criticisms by Mr SImons follow a public row over criticism of Ofsted, which led chief inspector SIr Michael Wilshaw to claim he “spitting blood” over what he believed were briefings against the organisation coming from within the DfE. The row followed reports that think-tanks, including Policy Exchange, were set to criticise Ofsted in upcoming reports.

A recent blog by Loic Menzies, director of education consultancy LKMco, also found several references in recent Ofsted reports in which schools are praised for linking pay with student attainment.

He argued that there were instances of Ofsted applying “soft” pressure to schools, such as where “comments tend to be made in the context of praise for where pay and performance are linked”. This, he said, amounted to “prescription under a cloak of autonomy”.

Darren Northcott, a national education official at the NASUWT union, told the event that he agreed Ofsted had a “really narrow focus on pupil performance” in relation to performance pay.

Marcus Bell, director for teachers and teaching at the Department for Education, who also spoke at the forum, said he was “not aware that [Ofsted] are asking schools to take a particular approach to performance pay.”

An Ofsted spokeswoman insisted that inspectors “do not consider or report on any individual teacher’s performance or whether the teaching of an individual teacher is reflected in their salary progression”.

“Inspectors may, however, report on how well governors or school leaders are implementing their own arrangements,” she added.

“Inspectors will also usually consider the extent to which the headteacher ensures that all staff undergo performance management procedures, which enable them to benefit from appropriate professional development... Where teachers’ performance is good, inspectors will expect to see evidence that this is recognised through the performance management process.”