MINISTERS face High Court action by the National Union of Teachers who want to block new rules forcing teachers to assess each other for a pound;2,000 pay rise.

The duty, which would affect department heads and other senior staff, will be included in all teacher contracts following the introduction of the performance-pay threshold.

It comes as a double blow to senior teachers who were this week warned they could be denied the automatic pound;2,000 rise many ex-pected because heads believe they cannot afford it. Instead they will have to apply to cross the threshold with junior colleagues.

Schools minister Estelle Morris provoked a furious reaction this week by creating the new duty of “assisting the headteacher in carrying out threshold assessments of other teachers”.

The clause was rushed into contracts after Ms Morris gained the agreement of the School Teachers’ Review Body that formal consultation was not required. She argues it is central to the pay structure, which has already been agreed.

The NUT has applied for a judicial review to halt the regulations being put in place on April 1. It hopes for a hearing before a High Court judge early next week.

The National Association of Schoolmasters Union of Women Teachers called the move “outrageous” and accused ministers of trying to sneak it through at the last minute. Ms Morris wrote to the review body on March 13.

“This will inflame the situatio,” NASUWT general secretary Nigel de Gruchy said. “Teachers will view it with a lot of suspicion and hostility.” The Association of Teachers and Lecturers also said that such a late addition to contracts was unacceptable.

In a letter to the review body chairman Tony Vineall last week, Ms Morris called the duty “an inevitable consequence” of the threshold system. “If those duties did not exist, the teachers’ pay and conditions document would be inconsistent in providing for the threshold but not the means of making it work,” she wrote.

She was backed by the National Association of Head Teachers, whose general secretary, David Hart, said: “It cannot have come as a shock to anyone. How can heads in the majority of schools sign off assessments against all eight threshold standards without an input from senior teachers?”

Ministers are expected to sign the Order in the next few days, and it will go to schools in early April.

The Order also cements the leadership scale, which covers heads, deputies and, for the first time, senior school managers who will get a pound;2,000 pay rise to maintain the pay gap with junior colleagues who cross the threshold.

But the rise attracts only a one-off grant, while threshold pay rises get continued funding from the Department for Education and Employment.

“Heads will say it’s better for their senior staff to go through the threshold,” Mr Hart said. “I think we will see significant but not dramatic numbers of staff joining the leadership group.”