It shows that half a million hours of PE lessons were lost in the past year because more time was spent on literacy and numeracy.

And sports teachers have warned that more PE time could be cut from September, as schools concentrate on the new numeracy hour.

'Insufficient support'

The survey, funded by Sport England, showed that a third of 1,500 English primary schools which responded had reduced the time they devoted to PE in the past year.

Of these, half had lost 30 minutes of PE each week, and another 20% had lost an hour a week.

There are concerns about children's physical development

A third of the schools said there was insuffiicient support available for teachers to become confident and competent to teach PE.

And a quarter reported that they did not have enough qualified staff to teach the subject.

Last year, the government suspended the national curriculum "orders" specifying what primary schools must teach in compulsory subjects such as PE.

New "orders" will not be imposed until September 2000, and earlier this year, David Hart, general secretary of the National Association of Head Teachers, warned that this "must not lead to schools being forced to produce literate and numerate but unfit Philistines".

'Valuable ground lost'

The survey was carried out by the Sport and Physical Education Network, which represents sports education organisations.

Its convenor, Professor Margaret Talbot, who is head of sport at Leeds Metropolitan University, said she expected the position to become "even bleaker" in the new academic year.

"The orders will be reinstated for September 2000, but then PE will have lost valuable ground and many schools will be ill prepared to deliver the new PE curriculum.

"PE is the only subject to support children's physical development, but research also shows that it is positively correlated with improved cognitive and social development.

"Children of this age need PE and research shows their academic work improves when they get it regularly."

But a spokesman for the Education Department denied that PE in primary schools was collapsing.

He said: "The key point is that we took a quite deliberate decision to focus for two years on literacy and numeracy.

'Schools have to be trusted'

"We had a situation where 40% of children were leaving primary school without having a grasp of the basics.

"That was a national scandal and it had to be addressed by making sure schools were devoting the necessary time to literacy and numeracy.

"PE remains compulsory in primary schools. But they have to be trusted to ensure that they provide a balanced timetable."

From September 2000, primary schools would be expected to ensure that children had two hours of PE a week, either during the school day or in after-school clubs.