It has now overtaken workload and poor behaviour as the biggest problem facing schools, the poll conducted for the National Union of Teachers shows.

A quarter of 873 teachers surveyed cited funding as the key problem, compared to fewer than one in six who named workload and one in seven who said discipline.

“Remodelling the workforce looks good on paper but there is no money to do it,” one said.

Another commented: “I am tired of having to cut corners with the school budget.”

Government spending on schools has increased by more than pound;800 per pupil since Labour came to power.

But rising costs and changes to the funding system last year left many schools struggling to make ends meet.

In an effort to draw a line under the issue before the next election, Charles Clarke, the Education Secretary, promised that all schools would receive a budget increase of at least 3.4 per cent per pupil this year.

Education spending is set to increase by a further pound;8.5 billion by 2008.

Despite ministers’ efforts, almost half of heads questioned by Mori said funding was their number one concern, compared to 22 per cent of classroom teachers.

Primary teachers were more likely to be concerned about funding than their secondary colleagues.

Other issues of concern to teachers included pay, league tables, inspection and professional morale, although each was mentioned by fewer than one in 10 of those surveyed.

Doug McAvoy, NUT general secretary, said the poll showed teachers’

confidence had not been restored following last year’s funding crisis.

“These results should come as no surprise to the Government.

“Teachers and heads have no confidence in the Government’s funding promises and are concerned that the costs of the workload agreement will create another crisis,” he said.

Most of the costs associated with the workload agreement are deferred until September 2005 when schools will be expected to give all teachers the equivalent of half a day each week for preparation and marking.