Teachers at a Bradford secondary school are being intimidated by a group of disruptive pupils, a union claims.

Education watchdog Ofsted will next month place Queensbury School into special measures following a damning report by inspectors who spent two days at the school in May.

Today Pam Milner, Bradford branch secretary for the NASUWT, said she has been contacted by several teachers at the school who have spoken of their fears for their safety after confrontations with some pupils. Mrs Milner said: “Some of our members have been in touch with us to say they feel vulnerable. When behaviour is not as it should be, anyone is at risk.

“If there are any particularly volatile children and they are not in a climate where there is a controlled atmosphere, then some of those children are very easily sparked into violence or abuse.”

Mrs Milner said staff at the school had contacted her directly to seek advice after being involved in confrontational incidents with pupils.

She said some staff had told her an “atmosphere of intimidation” existed when working with a small group of pupils in the school. But Mrs Milner stressed staff had expressed confidence that new head Alan Worthington, appointed in the spring, had “the ability to lead” and “would redress the balance”.

In June 2007, standards at Queensbury were said to be “inadequate” following a visit by representatives of the education watchdog, which awarded the school a Notice to Improve.

Full details on Ofsted’s decision to downgrade the school further to special measures will be made available to parents at the beginning of next month as the Government body’s report has yet to be made publicly available.

Schools in special measures are judged to be failing their pupils.

In December last year, the Telegraph & Argus reported that then Queensbury head Denise Shipton resigned after an internal investigation.

Mr Worthington said the school had recently been inspected but said it would be “inappropriate to comment at this stage as the report had not yet been published”.

Queensbury School governor, Councillor Michael Walls, who resigned his position on Friday, confirmed the school had been placed in special measures, but stressed that he believed it had “improved vastly”.

“I am not happy about this, because I know things have improved,” said Coun Walls.

He said he believed the inspectors had honed in on “pupil behaviour”, and added: “When they come we are obviously dependent on what happens in the school on that day.”

Coun Walls said Mr Worthington and his staff had put a “tremendous amount of work in” in a bid to turn Queensbury’s fortunes around.

Mr Worthington is the school’s sixth head teacher in the past nine years.

Ian Murch, Bradford branch secretary of the NUT, said current staff had been forced to deal with “the legacies of the past”, but said he had confidence that they were doing their best to address them.

In reference to the school being placed in special measures, he added: “It is very disappointing but we think the school is doing things which will make things better and it’s important parents have confidence in the school. Turning it round and regaining the confidence of the local community is a difficult job. But I have confidence that the school will be able to do that.”

An Education Bradford spokesman said: “An inspection has taken place and a report has been produced. As it has not yet been published it would be inappropriate to comment at the present time.”

A Bradford Council spokesman said the authority would also not comment until the full Ofsted report was made public.

Queensbury is the only secondary school in Bradford currently in special measures.