Mr Brown told MPs that the extra cash was available because the Government had not spent all the money it raised from the windfall tax.

"This lower unemployment means we can allocate new money to every school of every constituency in the country," he declared.

Unions applauded the announcement.

David Hart, general secretary of the National Association of Head Teachers, said the money would make "one hell of a difference".

He added: "It will certainly go a long way to reducing the backlog of repairs and maintenance that has built up over the last decade.

"It's good news for pupils who deserve to be educated in decent surroundings and good news for teachers who deserve to work in the best possible climate."

John Dunford, general secretary of the Secondary Heads Association, said: "This is very welcome, as is the fact that it is going directly to schools.

"Much-needed repairs will be carried out."

Nigel de Gruchy, general secretary of the National Association of Schoolmasters Union of Women Teachers, was pleased with the extra cash for repairs but added: "He really should have held a bit back to cope with the ever-increasing problems of teachers' pay."