Graeme Paton reports.
The Government's academies programme has been dealt a fresh blow after building work at one of the flagship schools was halted in a row over funding.
The construction company behind St Paul's academy in Greenwich, south-east London, downed tools after it emerged that the school's budget would not cover building expenses.
Critics said there were fears that costs - said to total pound;31 million in a funding agreement signed between ministers and the school's sponsors 15 months ago - were spiralling out of control.
The Department for Education and Skills now faces the prospect of increasing its own contribution or altering plans for the school to ensure it opens in September 2007.
It is the latest controversy to hit St Paul's. Last year The TES revealed that the Roman Catholic archdiocese of Southwark, its sponsor, was contributing just pound;200,000 towards the school, rather than the pound;2m being invested by most other academy backers. The remaining pound;1.8m is being met by local taxpayers.
Its building problems will increase pressure on academies, which are independent state schools, part-sponsored by private finance, following criticism over "excessive" costs elsewhere.
One school, Haberdashers' Aske's Knights academy, being built in south London, is due to cost pound;38m, and the Bexley business academy, which opened in 2002, cost pound;35m.
The Southwark diocese said that the St Paul's building programme, led by EC Harris, the construction project managers, had been halted while costs are re-assessed.
The diocese blamed inflationary pressures for the delay and said there was a possibility that the new school would not be completed in time.
The academy replaced St Paul's Catholic comprehensive in September last year and opened in the former school's buildings. Under existing plans, its new buildings will be built on the playing field of nearby Abbey Wood comprehensive, a non-denominational school. The academy will move in next September and Abbey Wood will close in 2009.
Sue Harry, head of Abbey Wood, who has opposed the academy plan, said contractors moved on to the playing field earlier this year, but suddenly packed up two weeks ago.
The DfES refused to disclose full details of the walk-out, saying only that there had been a "temporary stop in construction activity while effective use of resources is reviewed".
Greenwich council would only say that it was "disappointed to learn of a potential delay".
According to last February's funding agreement, the specification of the academy may be altered to cut costs if it goes over budget. The DfES and sponsors could also step in with more money.
Mrs Harry said she was surprised at the size of the original estimate, compared to higher costs at academies elsewhere. "Clearly something has gone wrong, but unfortunately, any delay to the academy will not affect the decision to close our school," she said.
Tim Woodcock, divisional secretary of the National Union of Teachers, said:
"If this building starts spiralling out of control, who is going to foot the bill? We need to know that as more is spent on the academy, money is not simply removed from schools' budgets elsewhere."
Powerless: Sue Harry, head of Abbey Wood, opposes the building of an academy on her playing field, which will lead to her school's closure