A survey of 82 of England’s councils by the Times Educational Supplement suggests 335 of the 957 expanding primaries it received information on are losing outdoor space.
More pupils will use the same area in 54% of these schools, the survey says.The government says it has tightened rules on building on playing fields.
The figures come amid continuing concern about a squeeze on school places, particularly for primary-aged children. Many schools have had to take in extra classes, building temporary classrooms to accommodate the extra pupils.
The TES calculated that if the figures were extrapolated to the whole of England, it would mean 213,750 children would have less space per head in their schools.
Last year, a study by the National Audit Office (NAO) warned that by September 2014 an estimated extra 256,000 primary and secondary school places would be needed to meet demand. Of these, 240,000 are required in primary schools, with more than a third needed in London alone.
The Department for Education has made about £5bn available to councils to create new school places, and 212,000 new primary places were created between May 2010 and May last year.