The expansion will mean up to 10 contractors will be pre-approved to build the privately sponsored schools, up from the original six.

Six companies including Balfour Beatty, Carillion, Kier, Laing O'Rourke, Skanska and Wilmott Dixon were chosen under the existing £2bn framework, which ends in 2010.

Partnerships for Schools, the quango in charge of Building Schools for the Future (BSF), will launch a tender for the expanded framework early next year, with firms expected to be in place and bidding for work from October 2009.