Serious doubts have been raised over whether the Assembly government's commitment to protect school budgets can bridge the per-pupil funding gap with England.
In last week's draft budget, the Government protected school budgets, both within the education department and through the Revenue Support Grant to local authorities, by one per cent above the rate of change in the Welsh budget.
It means funding for schools will increase from pound;1.83 billion to pound;1.9 billion by 201314.
Although the pledge fulfils first minister Carwyn Jones's election promise, many educationalists think it will fail to have the desired impact on the pound;527-per-pupil funding gap with England.
David Reynolds, professor of education at Plymouth University, said the gap may continue to grow because of the protection given to school budgets in England in Westminster's comprehensive spending review.
Although the gap currently stands at pound;527 per pupil, that figure will be revised when new comparative statistics are released in January, and many think the true figure is closer to pound;550 per pupil.
Professor Reynolds, a former Assembly government adviser, said: "I think ministers have done what they said they would (to protect school funding) and that's impressive. But I'm not certain these things will make a difference to the funding gap.
"It's very difficult to say because we don't know what the English figures are. However, if expenditure does stay steady in real terms, then the gap may widen."
Dr Philip Dixon, director of teaching union ATL Cymru, said the "jury is still out".
"We will have to wait and see what impact other cuts in Westminster and Cardiff Bay will have on the situation," he said. "I think both governments will indulge in smoke and mirrors to cover up some of the more unpalatable truths."
Both NASUWT Cymru and ASCL Cymru said decisions taken at local-authority level will determine how much cash actually reaches schools.
Recently, TES Cymru revealed that councils had promised they would stop holding on to education funding and delegate more cash to their schools.
But David Evans, secretary of NUT Cymru, said: "I'm not sure that local authorities are going to be able to do this because of the squeeze on their budgets elsewhere. We may well see local authorities using education cash in other areas."
By 201314, local government in Wales will see its revenue funding return to just below 201011 cash levels, equivalent to a 7.1 per cent cut in real terms.
A statement from the Welsh Local Government Association said: "The protection being given to education and social care is welcomed, but councils continue to be concerned that other services will be hit harder than the draft budget would suggest once the protection has been made.
"Increasing demand for council services and rising citizen expectations mean that pressure on local services is higher than ever."
The Conservatives favour direct funding of schools, bypassing local education authorities to ensure money makes it directly to heads, who can set their own priorities.
Education minister Leighton Andrews said: "We have been strategic and pragmatic in the way we allocate our funding. By protecting schools, skills and early years budgets, while honouring our ongoing commitments, we will continue to make Wales an education success story."
- Original headline: Funding gap looks set to go on growing despite budget pledge