Jeremy Corbyn has claimed that children are being “crammed in classrooms like sardines” and pledged to keep class sizes down if he wins the general election, in the latest of a series of high-profile interventions on education issues.

The Labour leader claims Government figures show more than 40,000 primary school children in England were taught in classes of 36 or more last year, up from 38,500 in 2015, blaming "broken promises" by the government.

"Seven years of Tory failure and broken promises have left our schools in a terrible state," claims the Labour leader.

"Hundreds of thousands of our children are paying the price, crammed into classrooms like sardines.

"The Prime Minister herself has said that super-sized classes are proof of a school system in a crisis. And that's what we've got on the Tories' watch.

"School leaders and teachers have said that Tory cuts to school budgets will mean class sizes will be forced to grow even larger. We cannot risk our children's education in this way."

In his speech, Mr Corbyn appeared to confuse some of the statistics released earlier by his party, inadvertently overstating the number of children in large classes.

Corbyn has pledged to stand up for all children by “building a schools system for everyone, keeping class sizes down and making sure schools and teachers have the resources they need to ensure that every child, whatever their background, has access to a world-class education”.

It comes after John McDonnell, the shadow chancellor, promised teachers at the NUT conference in Cardiff that a Corbyn government will “fully fund” schools, and Angela Rayner, the shadow education secretary, indicated that Labour will attempt to fix the “broken” school place planning system.

However, a Conservative Party spokesman claimed: "This is a massive own goal from Labour. In Wales, where they administer schools with the Lib Dems, the numbers of infants in large classes has risen by 18% in just three years.

"Of course, we are not complacent about the situation in England. There is more to do and that's why we are spending a record amount on schools - something we can afford to do because of our careful management of the nation's finances."