The Welsh Assembly Government says education spending is at a high
Cchildren in Wales receive an average of £527 less per pupil in funding than in England, new statistics show.
The increased spending gap was described as "scandalous" by the director of a teaching union.
Philip Dixon of the Association of Teachers and Lecturers Cymru (ATL) said Welsh education was at "crisis point".
The assembly government said spending on education in Wales had never been higher but it recognised the importance of more funding "to the front lines".
Dr Dixon said the effects of the spending gap on Welsh schools were plain to see.
He said: "This gap is scandalous - no other word will do. We are now spending over £500 less per pupil in Wales than in England."
Wales should be spending more than England to tackle the effects of poverty and deprivation
Inspectors from Welsh schools watchdog Estyn have noted shortcomings in more than 40% of secondary school buildings inspections.
Dr Dixon added: "We are glad that the new first minister [Carwyn Jones] has pledged more money to education because we have now reached a crisis point.
"ATL believes there should be a spending gap between England and Wales - Wales should be spending more than England to tackle the effects of poverty and deprivation."
Education spending 'never higher'
An assembly government spokesman said spending on education in Wales had increased by 71% since 1999-2000.
But the spokesman said the government recognised the importance of getting more education funding "to the front lines".
He said: "We are taking steps to address this, and recently announced a major independent review of how education funding in Wales is allocated to schools, colleges and universities.
"The first minister and education minister [Leighton Andrews] have also made a significant commitment to education, promising to increase spending by 1% above the block grant we receive from the UK Government from the 2011-12 financial year."
But Conservative education spokesman Paul Davies said: "The gap in spending per pupil between Wales and England is unacceptably high - and getting wider.
"Unless we close it children in Wales will continue to be denied the same sort of learning opportunities enjoyed by pupils across the border."