A Labour government will act to limit primary school classes in England to no more than 30 pupils if the party gains power at the general election in May, Ed Miliband is pledging.

The Labour leader said the party will create thousands of new school places - including ones in popular, over-subscribed schools - enabling it to cap class sizes for five, six and seven year olds.

He will use a speech at his old secondary school in north London to say a Labour government would fund the scheme by ending the building of new free schools - introduced by the coalition - in areas where there is a surplus of places.

However the Conservatives said primary school classes were already capped at 30, and that Labour's proposals would mean getting rid of 'sensible exceptions' designed to ensure the children of armed forces personnel got places and that twins were not split up.

The move is part of Labour's plan for education in England, including the appointment of new local 'directors of standards' to drive up schools' performance.

Mr Miliband's intervention comes as Nick Clegg is promising to put education at the centre of the Liberal Democrats' general election campaign - suggesting that it could emerge as one of the key election battlegrounds.

The previous Labour government originally introduced legislation in the 1990s limiting primary school class sizes to a maximum of 30, although the rules have been relaxed under the coalition.

Labour says that there are now around than 90,000 pupils aged five to seven being taught in classes of more than 30.

Speaking at Haverstock School in Camden, Mr Miliband said that unless action is taken the problem will get much worse.

'Successful teaching and classroom discipline is made harder when classes are so much bigger,' he says.

'Since 2010, the number of the youngest children taught in classes bigger than 30 has gone up by almost 60,000. It is treble the number it was. And it is set to get far worse.

'Currently, the Government is spending money on new free schools in areas where there are surplus places. This simply makes no sense when class sizes are rising in the way they are. Or when people can't get their kids into the good schools they want.

'So by ending the scandalous waste of money from building new schools in areas of surplus places, we will create more places where they are needed.'

A Conservative spokesman said: 'Ed Miliband's policy has collapsed within minutes - primary school sizes are already capped at 30.

'Are Labour saying they will scrap sensible exceptions like those that ensure armed forces children get a place at primary school, or ensure that twins aren't forced apart?

'This incompetence and chaos shows exactly why Ed Miliband is simply not up to the job.'

In other measures, Mr Miliband will say that under Labour, all state schools in England, including free schools and academies, will be accountable to a new, local director of standards who parent bodies will be able to call in if they fear their school is failing.

At the same time, he will say that all head teachers would be given key freedoms currently given to academy heads.

'We should always be the eternal warriors for higher standards,' Mr Miliband will say.

'It is up to the next Labour government to improve standards in every part of the country not by turning the clock back but by ensuring proper accountability within the diversity of provision that we have.

'We want all headteachers to have the powers currently given to academy heads. But we also want every school to be locally accountable. That is what our new directors of school standards will ensure.'