Derelict offices and hospitals could be turned into new schools if the demand for primary school places continues to rise, it has emerged.

Richmond's education chief has said he is on the lookout for new school sites as the birth rate rockets and fewer parents opt to send their children to private schools during the recession.

"I don't pass a disused office building or hospital without thinking if it could make a school," said Councillor Malcolm Eady, Richmond Council's cabinet member for education and children's services.

"But we do not have the money to buy them or build them.

"We need to provide extra classes and there will be different decisions in different areas [of the borough]."

New figures show that between 2002 and 2007 there was a 20 per cent rise in Richmond's birth rate. Meanwhile, just 22 per cent of parents are now choosing private schools - that figure was previously 30 per cent.

In response, the council has had to find places for 150 extra youngsters and has added bulge classes to Lowther Primary School, Barnes, Chase Bridge Primary School, Whitton, St Mary's CE Primary School and Orleans Infant School, both in Twickenham, and St Elizabeth's RC Primary School, Richmond.

Coun Eady said Darell Primary School, Kew, would also be taking on seven extra children and 30 to 40 still don't have a place but he expected they would soon.

Holy Trinity CE Primary School, Richmond, and St Mary's and St Peter's CE Primary School, Teddington, will also have bulge classes and will be expanded into larger schools by September 2010 and September 2011 respectively.

The move comes as part of the council's £32m primary school revamp, during which there is planned an expansion of Chase Bridge, a merger of Stanley Infant and Junior Schools into one large school and Orleans and St Stephen's Junior School becoming all-through primary schools if proposals are agreed.

The Government announced last year it would be giving Richmond Council £8.3m for planned rebuilding and refurbishment projects between 2009 and 2011, and additional funding of £8.9m to build new schools.

The Government will also make £200m available for primary school expansion across the country - which authorities will have to bid for in the next two weeks - but Coun Eady said this "falls far short of what is required".

He explained this money would be divided between dozens of councils and he expected Richmond to pick up a small share, which would do little to help the situation.

Susan Kramer, MP for Richmond Park, said she would press the Government to give Richmond the money it needed.

Coun Eady said he believed there had been a further rise in the birth rate to 12.4 per cent in the past three years. And that, coupled with an 8 per cent drop in children going to private schools, means the borough could need 14 extra reception classes.

"The problem we have is what we do in the future," he said.

"We do not have another £32m lying around.

"We could borrow it but we would have to put council tax up to pay for it and the Government would cap it or we find it by cutting front line services.

"We know the Government will cut local authority spending in the next two to three years, we are already looking for savings and to have to make £32m more is not on.

"We have to be cleverer, we have to find ways of providing these places without re-building whole schools."