Official figures show the ranks of those teachers without qualified teacher status swelled by a third between January 20023 at the same time as the number of qualified teachers in primary schools fell for the first time in five years.
The increase came before the signing of the agreement to cut teachers'
workload which the National Union of Teachers has warned will lead to teachers being replaced by unqualified staff.
John Howson, visiting professor at Oxford Brookes university, said the figures called into doubt the Government's promise to recruit an additional 10,000 teachers.
The number of full-time regular teachers with QTS has increased by only 409 since 2001.
London was the area with the fastest growth in teachers without QTS.
Overseas teachers helped numbers in the capital increase by 50 per cent to 5,650. In total there are now more than 15,300 unqualified teachers across the country.
In primary schools teachers without QTS have replaced qualified staff, whose numbers fell by 1,200 to 192,000.
Experts said that the reduction in qualified teacher numbers were a result of falling pupil rolls and the consequent cuts in funding.
John Bangs, NUT head of education, said: "This is the start of a trend that makes a mockery of the Government's commitment to increase the number of qualified teachers. It should be the responsibility of all teacher unions not just the NUT to safeguard the jobs of qualified teachers."
But Chris Keates, deputy general secretary of the National Association of Schoolmasters Union of Women Teachers, said that the figures reflect recruitment and retention problems. "NASUWT has always maintained that the improvements in conditions of service heralded by the contractual changes in the national agreement should start to increase the availability of qualified teachers."
A Government spokeswoman said that there are now more teachers with QTS than at any time since 1984 and that most overseas teachers are English speaking, high-quality and experienced:"These people play a very valuable role in schools," she said.