Image caption A surging birth rate has seen primary schools under pressure to expand

Pupils in England could be taught in bigger classes and by unqualified staff from next September, as a rising population puts pressure on school capacity, Labour has said.

Shadow Education Secretary Stephen Twigg said an extra 15,000 teachers would be needed by 2014-15 as an additional 256,000 pupils start school.

Mr Twigg said this was a "real and growing threat to school standards".

But the Department for Education said his claims were "ridiculous".

Mr Twigg's comments come less than two weeks after the National Audit Office warned that a quarter of a million extra school places would be needed in England by autumn 2014.

The spending watchdog said one in five primary schools in England was full or near capacity and there were signs of "real strain" on places.

'Cutting quality'

Labour says its calculations, based on pupil population estimates, show around 14,545 teachers are needed.

When this is added to the 520 vacancies the party says are already in the system, it means that around 15,065 teachers will be required by the next election.

Addressing the ATL's conference in Liverpool on Wednesday, Mr Twigg said: "Michael Gove is presiding over a crisis in the teaching profession - with a huge shortage of teachers, and unqualified teachers getting into the classroom.

"Pupils deserve far better. Unless this crisis is addressed head on, pupils will be in bigger class sizes or face being taught by people without teaching qualifications.

"This is a real and growing threat to school standards.

"All the international evidence shows that the quality of teaching makes the biggest difference to results. We cannot let the next generation down by cutting teacher quality."

Teacher morale

Mr Twigg criticised the education secretary for allowing free schools and academies the freedom to employ staff who do not have qualified teacher status.

Mr Twigg also hit out at the government, saying it has "pitched itself against" the teaching profession, "against the very people it needs onside to deliver the sort of change that our education system needs".

Mr Twigg said politicians have a duty "not to undermine the professionalism that underpins the status and morale of teachers".

"Heads, teachers and the wider school workforce are the people who make the biggest difference to our children's educational outcomes.

"All too often they are undermined by politicians and a media obsessed with talking down our education system.

"A minister would not instruct a surgeon on best practice in an operating theatre, yet, all too often, ministers want to prescribe methods for the delivery of teaching and learning in our classrooms."

A Department of Education spokesperson said: "Teaching is a highly attractive profession - more top graduates and career changers than ever before are coming into teaching, and vacancy rates are at their lowest since 2005.

"Teacher training applications for fee-based postgraduate courses in England are up by more than 1,500 applicants on this time last year.

"We have invested £4m to help existing teachers develop their skills. Plus we are spending £5bn by 2015 on creating new school places — more than double the amount spent by the previous government in the same timeframe.

"We trust head teachers to employ the right mix of staff for their schools. That is why we have given free schools and academies the same freedoms the best independent schools enjoy to hire great linguists, computer scientists, engineers and others who can inspire their pupils."

On Tuesday, Liberal Democrat Schools Minister David Laws praised the teaching profession, saying ministers "appreciate the job you do - genuinely and sincerely."