Ministers have sparked outrage by limiting the latest computer subsidy scheme to key stage 3 maths staff.

Teachers who missed out on pound;500 subsidies from the pound;20 million scheme last year were expecting another chance to apply. But ministers said the second phase of the project, costing pound;15m, would be dictated by “key Government priorities”.

Michael Wills, the learning and technology minister, said the move recognised the importance of maths teachers and the need to support them.

But Shaun Kirby, a secondary science teacher from Dover, said he and thousands of others were being discriminated against. “It is rapidly becoming essential to have a computer to teach effectively,” he said.

Bob Linnell, head of Ashmanor secondary in Surrey, added: ” know several teachers who are very disappointed that they can’t apply - they feel misled.” More than 28,000 teachers got the subsidy last year, when the scheme was open to any who agreed to sign up for a technology training programme. The original scheme closed in April.

This first phase provoked controversy after it emerged that teachers would have to pay tax on the subsidy. After ministers were accused of poor management, the Government eventually agreed to pick up the tax bill.

Teacher unions have attacked the restrictions on the second phase. But the Department for Education and Employment insisted the move did not imply it considered other subjects less important than maths.

A spokesman added the pound;15m initiative would help another 17,000 teachers to get their own computers.

Maths teachers have until February 23 to register for the scheme.