Teacher vacancies in secondary schools have trebled since 1997, according to government figures published on Wednesday.

Although there are 18,000 more secondary teachers, there were 1,942 unfilled full-time posts in secondary schools in England this January compared with 649 vacancies when Labour came to power.

A spokeswoman for the Department for Education and Skills told ePolitix.com: "There are many, many more teachers in our schools than six years ago.

"Overall, the teacher vacancy rate is now under one per cent - down by quarter from last year.

"While the number of secondary teacher vacancies is higher than in 1997, it has fallen in the last two years and, over the same period, there are 18,000 more full-time equivalent secondary teachers in our schools. This is good news for children and the standard of education that they are receiving.

"In total, we have 25,000 more teachers in our schools since 1997. There are also 80,000 more support staff and Ofsted say the quality of teaching has never been higher."

Damian Green, shadow education secretary, said: "As Charles Clarke celebrates his first anniversary as secretary of state for education, these shameful figures show that teacher vacancies have trebled under Labour.

"This is because of falling standards of discipline and too much intervention in the classroom by this government. That's why it is so difficult to retain teachers and that's why vacancies have trebled."We will give back power to head teachers to run their schools, and restore moral within the teaching profession by trusting teachers to do what they are best at: teaching."

Forum Response: Association of Teachers and Lecturers

Gerald Imison, ATL's deputy general secretary, told ePolitix.com: "The figures emphasise that the recruitment and retention of teachers remains crucial to the delivery of improved standards of education to our children. Just as important is that they are the right teachers because, particularly in secondary schools, far too many lessons are taught by qualified teachers who do not have the full understanding of the subject matter that is really necessary.

"What we must emphasise very clearly is that the use of other adults in the classroom can never ever be a substitute for the qualified teacher and that the use of the recent agreement on workload and standards is not a licence to use inappropriate staff.

"We currently have two problems: the government is working with us through the national agreement to reduce the burden on existing teachers to give them more time for their teaching. It cannot afford, however, to take its eye off the second - we need more qualified teachers. Behind both problems lies the inescapable fact that education is the nation's investment in its future and the more resources you invest, the greater will be your return."

Forum Response: National Union of Teachers

Doug McAvoy, general secretary of the National Union of Teachers, said: "The government has criticised the studies done by others which have emphasised the depth of the problem being faced by our schools of job losses and the difficulties of staff retention.

"It has tried to hide these figures, but for every child in the schools affected they are a reality of everyday life."