Local authorities all over the country are being forced to accept new academies despite falling school rolls which are pushing the number of surplus places sky high.

In many parts of England, education officials believe that if they want to reorganise schools to cut the numbers of empty desks, their only chance of acquiring the necessary funding is to feature an academy in their plans.

Some authorities say that their efforts to cut surplus places are being thwarted because of government policies. In some areas, plans to open academies are creating places just as the local authority is trying to cut back.

At Grimsby in north-east Lincolnshire, there are plans for two new academies which will replace existing schools as part of a reorganisation designed to cut surplus places. Martyn Yeatman, the area’s National Union of Teachers secretary, said the academy plan was the only option on the table.

“It’s an academy or nothing,” he said. “The authority put forward plans for secondary schools four or five years ago and they were knocked back. Then along came the academies. It’s been said quite openly, both at meetings with the union and with staff, ‘If you don’t want this, we will see if there’s anywhere else we can put this new school.’ That’s the bribe.”

Lancashire county council, which needs to cut up to 1,000 surplus places, has proposed merging two secondary schools in Preston into a single academy. Alan Whittaker, the deputy leader of the county council, said this seemed the only practical option.

“I’m a dyed-in-the-wool municipal socialist, but the pragmatist in me says that if I can lever in pound;15-pound;20 million worth of new resources to address the issues of a couple of schools, that’s the best thing to do for those children.

“We have a standing order from the DfES (Department for Education and Skills) to cut these places, and what they have said to us is that if we go for an academy in addressing the issue, then that would be a way forward.”

Official figures show that a shortage of pupils is beginning to have a serious effect on schools. Nationally, the number of surplus places is at its highest level since 1998 and is likely to continue rising for at least three more years.

There are 758,000 surplus places in England, and a further 500,000 are expected in primaries by 2010. In many areas teachers are facing the prospect of job cuts as local authorities try to manage the problem.

Teachers in Ceredigion in west Wales were told this month that 16 jobs would go at the end of this term. A further 56 jobs were threatened in Cardiff as the city council prepares for a big reorganisation.

While it seems likely that more school closures and staff cuts will follow, falling rolls mean schools are enjoying the bonus of smaller class sizes.

The latest class size statistics, published last week, show the proportion of primary pupils in classes of more than 30 had fallen from one in three 10 years ago to one in seven this year. The average class size in primary schools fell from 27.8 pupils in 1998 to 26.2 in January this year.

In secondary schools, the average class size dropped from 21.9 to 21.3 pupils over the same period.

Teacher unions have argued that rather than closing schools and cutting jobs, local authorities should take advantage of the situation to improve pupil-teacher ratios. Steve Sinnott, the general secretary of the National Union of Teachers, said: “One of our arguments has always been that falling rolls provide an opportunity to reduce class sizes.”

John Dunford, the general secretary of the Association of School and College Leaders, said: “Individual schools can make decisions about staff appointments now, so there need not be the redeployment of staff that there was in the 1980s. There will also be many more federations of schools.

Politicians don’t make themselves popular by closing schools.”