Schools in London are under pressure to use playground space for new classrooms, the Commons education committee has been warned.

Official predictions show that the number of pupils in primary schools began to increase in 2010. By 2021 there are due to be 4.808m pupils in primaries - 18 per cent more than last year. In some areas one in five pupils will not have a place if nothing is done, according to the Local Government Association. 

Siobhan McDonagh (pictured), MP for Mitcham and Morden, speaking at the Commons Education Select Committee today, said: “One of the pressures that is coming up in better off areas like Wimbledon, is people’s concerns about playground and outside school space.

“Many schools are having to use some of that space to provide more classes.”

However, David Laws, schools minister, replied: “We place a very high premium on making sure schools have enough outdoor space for sport and other activities. We have to authorise one by one requests from existing schools to use outdoor space to build any classrooms.”

He estimated that about 100 schools had been granted permission after recently asking to build on their sites.

The debate came after a public accounts committee report in June found 64 per cent of local authorities said playground space had been reduced to provide new school places.

The London Borough of Merton has already expanded 16 primary schools, adding an extra class on each, and is due to expand four more by 2014. 

The government is providing £1.6bn for 2013 to 2015 to local authorities to provide additional school places. It also gave out an extra £820m of funding for additional new places in outstanding or good schools in areas where there is a need for more places.