By Sean Coughlan BBC News Online at the NUT conference, Harrogate

Teachers are warning that schools in England could face another round of funding shortages.

Teachers say that schools still lack adequate funding

Doug McAvoy, general secretary of the National Union of Teachers, has raised the spectre of the financial crisis that affected many schools last year.

He says schools do not have enough money to fund a planned reduction in teachers' workload.

And he accused Education Secretary Charles Clarke of being "childish" in refusing to negotiate with the teachers' union.

Mr Clarke has once again refused to attend the union's annual conference which is getting underway in Harrogate.

Mr McAvoy, who is to retire as general secretary this summer, says that the government is failing to keep its promise to provide adequate funding for schools.

Funding promise

"Although much publicised, the funding increase does not match what was promised," said Mr McAvoy.

Doug McAvoy accused the education secretary of being "childish"

John Bangs, one of the contenders to replace Mr McAvoy, said that there is a "real mis-match of expectations over funding between schools and government".

The union has commissioned a report into the funding implications of a deal to cut teachers' workload (which the NUT unlike other teachers' unions has refused to sign).

And the union says that many schools could face budget problems - particularly those which do not get extra grants, such as those supporting schools in deprived inner-city areas.

Small schools and schools with falling numbers of pupils could face financial difficulties, says the report.

There could also be problems for schools which have a large proportion of teachers on higher pay scales.

Re-training civil servants

But the report also reflects that local education authorities have been able to meet the government's target of a 4% increase in per pupil funding.

And it says that there are schools which have some "flexibility" in their budgets.

The union conference is set to debate school funding at the weekend - and it will hear the accusation that the government has also failed in its longer-term promises to increase education funding.

Mr McAvoy also attacked the suggestion that thousands of civil servants who could lose their jobs in a Whitehall shake-up could be re-trained as classroom assistants.

The union has campaigned to restrict the unsupervised use of classroom assistants - and has argued that only qualified teachers should be in charge of a class.