A majority of teachers are worried that performance-related pay will be unfair, researchers say.

Nearly two thirds of teachers questioned for a survey said they were opposed to performance pay in principle.

And more than two thirds said they believed the new pay system was a device for avoiding giving more money to all teachers.

Under the new pay scheme, which came into force last month, teachers need to pass through a quality "threshold" to receive a �2,000 pay rise and access to a higher pay scale.

Some teachers' opposition to the system caused friction at the annual conference of the National Union of Teachers last month when members voted for a strike ballot over performance pay.

Judicial review

The NUT has been given permission to mount a High Court challenge to the system.

It applied for a judicial review over the government's handling of the regulations, arguing that late changes to the legislation that introduces the system have not allowed the required period of consultation.

The survey of 3,000 teachers has been published in the London School of Economics' CentrePiece magazine.

It is part of a major study of performance-related pay being conducted by Professor David Marsden of the Centre for Economic Performance.

The findings also suggest that teachers are working an average of 14.8 hours a week overtime, making the average term-time working week more than 50 hours long.

Those who responded to the survey made it clear that the role of the teaching unions would be critical in determining whether performance-related pay was seen as fair by teachers.