More than half a million primary children in England are being taught in supersize classes, the Labour party has claimed.  

The analysis of official government figures, which shows that hundreds of thousands of pupils are being taught in one-teacher classes of more than 30 children, comes on the deadline day for parents to submit applications for children starting primary school.

“Over half-a-million children are now in supersize classes in primary schools, as class sizes continue to rise,” a Labour party spokesperson said. More than 2,700 London pupils are taught in classes of more than 40 - the highest number of any region in the country, according to the analysis. Sadiq Khan, Labour’s candidate for Mayor of London, has called for a London-wide oversight of school places.

“The system is approaching breaking point when London parents can see school gates from their front door, but can’t get their kids into that school.” he said. “It’s also unacceptable that children are being taught in detrimentally large classes.”

But a Conservative Party spokesman has said that 500,000 more school places have been created and accused the last Labour government of cutting funding by £150 million, scrapping almost 200,000 places.

Overall, 520,445 children aged between five and 11 are being taught in classes of at least 31 pupils, the Labour party said. Of these, 38,560 are in classes of 36 or more children and 14,824 are in classes with at least 40 youngsters.

A limit on infant school class sizes was introduced by Labour in the late 1990s, stating that no more than 30 youngsters should be in a class.

But under the rules, there are certain circumstances in which schools can legally waive the limit, and these have been extended in recent years.

Mary Bousted, general secretary of the ATL teaching union, said: “There is a limit to how far existing schools can expand. Many are already using school halls, music rooms and gyms for classrooms and building over their playing fields to accommodate extra children. 

“Children are being taught in portacabins and increasingly large classes, and until the government tackles the lack of school places, these problems will get worse.”

Christine Blower, general secretary of the NUT teaching union, said that the analysis would make “shocking reading for many parents”. “The blame for the shortage of school places and soaring class sizes lies at the door of the government which has stood by and done nothing to address the problem,” she added

A DfE spokesperson said: “Despite an increase in pupil numbers, we have been able to keep the average infant class size the same, at 27.4, and the number of unlawfully large infant classes actually has fallen - down 137 compared to 2009.”