Headteachers across Wales have been left reeling after a key fund to help them to raise standards was slashed by a third.
The Assembly government is reducing the money available through the Better Schools Fund (BSF) to pound;27.4 million in 201011, a cut of pound;12.2 million on the previous year.
Although the government warned in its draft budget last December that less money would be available, the full extent of the cut has only just become apparent.
In a memo to heads last week, education minister Leighton Andrews placed new restrictions on how the money can be spent, further limiting its use to schools.
Teaching unions attacked the government for making such a substantial cut just months before it rolls out the ambitious school-effectiveness framework, which aims to raise pupil attainment.
Since it was introduced in 2004, the Assembly government has provided more than pound;240 million through the BSF.
But in recent years the money available has gradually decreased and more limits have been put on what it can be spent on.
Many cash-strapped schools have come to rely on the extra funding for a range of uses, and headteachers' unions said the cut will hit them hard.
Anna Brychan, director of the NAHT Cymru, said: "Heads have known that something nasty was coming, but this is enormous. Most heads rely very heavily on every bit of their budget.
"There will be a lot of extremely worried school leaders wondering how they are going to fulfil the requirements of the school effectiveness framework."
Gareth Jones, secretary of the Association of School and College Leaders Cymru, said:
"It's slowly becoming clearer and clearer how severe the financial downturn is going to be for schools in Wales."
Mr Andrews said the Better Schools Fund must now focus on school effectiveness; implementing the Welsh-medium education strategy; and inclusion, safeguarding and promoting well-being.
Many schools used the cash to fund staff training, and many heads are worried about how it will now be funded.
The government has already axed the pound;3 million annual cash pot for continuing professional development through the General Teaching Council for Wales.
In a statement last month the education minister said the BSF will continue to provide cash to support the government's key strategic priorities for education, with a strong focus on innovation and support for new initiatives.
"These activities are agreed on a year by year basis with local authorities. This enables the fund to take account of emerging pressures and to redirect available resources."
An Assembly government spokeswoman said: "The BSF allocation was approved when the Assembly government budget was agreed by the National Assembly on 8 December. The total BSF programme value is pound;24.7million for 2010-11."