The government says its proposals will eventually allow a majority of teachers in England to earn salaries of up to £35,000.

But the National Union of Teachers, which is opposed to any proposals which link teachers' pay to the performance of pupils, argues that the figures do not add up.

Doug McAvoy: "The government's consultation is a sham, the proposals a deception and its figures flawed"

Its General Secretary, Doug McAvoy, warned members not to be tempted to back the deal by the prospect of higher salaries.

If a majority of teachers were to benefit, he said, it would cost considerably more than the £1 billion ministers have allocated over the next two years.

He also attacked the government's consultation exercise on the proposals, which are contained in a Green Paper published late last year.

"The government's Green Paper and its consultation exercise is dishonest," said Mr McAvoy.

"It does not ask teachers what they think of performance-related pay, nor does it tell them that performance-related pay will be rationed.

"No matter how good a teacher is, if the rationed funds are used up, the payment won't be made."