More than pound;22 million has been "wasted" training teachers who do not go on to teach in Wales, the Liberal Democrats have claimed.
Figures released by the party this week revealed that between 200405 and 200708, Wales trained an excess of almost 3,000 teachers, at a cost of more than pound;7,500 each.
Jenny Randerson, Liberal Democrat education spokeswoman, accused the Assembly government of being "wasteful and irresponsible" for spending money on teachers for whom there are no vacancies in Wales.
According to the Lib Dem figures, which are taken from the Higher Education Funding Council for Wales' Initial Teacher Training (ITT) statistics, between 200405 and 200708, Welsh universities trained 224 excess English teachers at a cost of pound;1.3 million, and 133 excess maths teachers at a cost of pound;1.1 million.
Ms Randerson said: "At a time when budgets are increasingly stretched, and with education spending already pound;500 per pupil less than in England, Wales can ill afford to be subsidising the English education system."
The comments follow a warning from the General Teaching Council for Wales earlier this year that there are too many trained teachers in the system who cannot secure work, particularly those who are trained to work in the primary sector.
Hayden Llewellyn, its deputy chief executive, said: "Unless there is a better balance between supply and demand, some new teachers are simply being trained for unemployment and resources are being wasted that could be used to enhance the skills of existing teachers."
But the Assembly government accused Ms Randerson of "high rhetoric and faux outrage".
A spokeswoman said: "This is not an accurate account of teacher training in Wales. The figures quoted are based on an employment snapshot at six months which is not a comprehensive employment record. Newly qualified teachers continue to take up employment six months after qualifying, for example.
"The figures also significantly over-estimate the number of qualified teachers not teaching in Wales by comparing all qualifier numbers against employment returns, which only covers 70 to 80 per cent of qualifiers."
Drastic cutbacks in ITT numbers were first recommended in 2006 by Professor John Furlong, an education expert at Oxford University.
In a controversial report, he said that in the previous four years employment of newly qualified primary teachers in Wales varied from 28 per cent to 41 per cent.
Professor Furlong said the Assembly government should aim to halve the 2005 number of primary ITT places by 2010 and cut secondary numbers by 25 per cent.
Although the government has continued to reduce primary ITT targets, the 50 per cent cut will not be put into effect due to factors including increased pupil numbers.
- Original headline: pound;22m `wasted' on training NQTs despite jobs shortage, Lib Dems claim