Welsh delegates from the National Union of Teachers will use their national conference this weekend to criticise the way schools in Wales are funded.
A new research paper launched today by the NUT Cymru at its conference in Cardiff shows a significant number of Welsh local authorities are spending less money on education than they receive from the Assembly government.
Each of Wales's 22 local authorities has its own formula for how it spends the cash it receives.
The research, by John Atkins, a consultant, found that 14 authorities are spending less on education than they are allocated - a discrepancy of about pound;66.4 million.
Welsh local authorities spend on average 9.5 per cent less per pupil than authorities in England, a proportion that has risen since devolution.
The report also points out that three years after a cross-party Assembly committee report on school funding, few of its 27 recommendations have been implemented. Mr Atkins said an alternative to the current "defective" system must be found if Wales is to tackle the problems caused by underfunded schools.
He called for a mixed national-local funding formula in which the direct costs of education, such as teachers, academic management and learning materials, are funded nationally, and the indirect costs, such as premises and administrative support, are funded locally.
"By doing this we can ensure that virtually all the money allocated originally for education in Wales will actually be spent on that provision," he said.
David Evans, the NUT's Wales secretary, said the situation would only get worse in the recession.
He called for talks with the Assembly government and the Welsh Local Government Association (WLGA) "to discuss real solutions that will address this problem".
Jenny Randerson, the Welsh Lib Dem education spokeswoman, said the funding variation created "very real" problems in Wales. She called for guaranteed funding to be targeted at the poorest pupils.
"Only then can we begin to break the cycle of poverty and underachievement," she said.
The NUT's report will put further pressure on the Assembly government to review school funding. Last year, TES Cymru revealed Welsh schools were spending up to Pounds 500 less per pupil than their English counterparts.
David Reynolds, professor of education at Plymouth University, who carried out the research for TES Cymru, said: "It is helpful that someone else has found a very similar story, and (Mr Atkins') research confirms the big funding differences between England and Wales."
A spokesperson for the Assembly government said the NUT report would inform how it builds on arrangements for school funding.
The WLGA was unavailable for comment, but has previously said that local authorities invest more in education than they get from the Assembly government, and that they are best placed to decide how the cash is spent.
NUT delegates from all over the UK will debate motions at the annual conference in Cardiff on themes including teacher workload, Sats tests and academies.
- Earlier this week, a North Wales teacher proposed a motion on violence and malicious intrusion into teachers' lives at the Association of Teachers and Lecturers' annual conference in Liverpool.
Maxine Bradshaw, a teacher at Ysgol Llywelyn in Rhyl, said teachers' homes and cars were being attacked.