A teachers’ union has raised serious concerns about the conduct of Ofsted inspectors investigating an alleged Islamist plot to take over schools in Birmingham.

Teachers in the schools being inspected over the “Trojan Horse” plot claims were allegedly told their school would be downgraded because they were “not teaching anti-terrorism”, while inspectors also asked pupils and teaching staff “leading questions” on their attitude towards homosexuality, according to Roger King, the NUT’s executive member for the city.

The claims follow the announcement that Sir Michael Wilshaw, Ofsted’s chief inspector, will be personally overseeing the watchdog’s investigation into 16 schools in the city.

The latest criticism comes after TES reported last month on concerns about the conduct of inspectors at Park View School (pictured) during an inspection.

The NUT is expected to debate an emergency motion expressing concern about the handling of the Trojan Horse allegations at its annual conference in Brighton tomorrow.

In a press conference this afternoon, Mr King said NUT members working in the schools had reported that inspectors had behaved inappropriately during the recent wave of inspections.

“The Ofsted team were going to the staff of [one of the schools] and saying: ‘We’re going to fail you.’ And some of the staff were saying: ‘Why are you failing us?’ And [Ofsted] were saying: ‘You’re not teaching anti-terrorism and therefore there’s a safeguarding issue in this school,” he said.

“I think that’s an inappropriate thing to do. That’s not what Ofsted are in there for. There are a number of things like that, like asking the staff: ‘Are you homophobic?’, asking the girl pupils who didn’t happen to be sitting next to boys: ‘Are you made to sit in different places?’”

“You do question how objective Ofsted were when they went into those schools,” Mr King added. NUT general secretary Christine Blower said the union would be raising members’ concerns with Ofsted.

In response to the allegations, an Ofsted spokesman said: “Inspectors are required to uphold the highest professional standards in their work and to ensure that everyone they encounter during inspections is treated fairly and with respect.

“These standards are assured through a code of conduct. Any concerns that a school has about the inspection should be raised during the inspection. If concerns have not been resolved, individuals or schools can raise a formal complaint with Ofsted in line with our published complaints policy.”

A report in today’s Sunday Telegraph claimed at least six of the schools being inspected would be put in special measures.

However Mr King said reports that Springfield Primary, where he is chair of governors, had been inspected were “rubbish”; its most recent inspection, he said, was two years ago.

Birmingham city council is carrying out its own investigation into 25 schools in the city, while education secretary Michael Gove has appointed former counter-terrorism police chief Peter Clarke to carry out a separate review, a decision described as “desperately unfortunate” by West Midlands police chief constable Chris Sims.