Union leaders say the collapse of Metronet costs �250,000 a day

The Rail, Martime and Transport Union (RMT) said the collapse could slow down the timetable to bring the Tube network to a suitable standard for the games.

The RMT submitted a motion to delegates at the TUC Congress in Brighton where it outlined its concerns.

But Transport for London (TfL) said the firm's break up would not affect 2012.

The union's leader Bob Crow said the consortium's collapse was costing around �250,000 a day.

'Expensive charade'

He also claimed �10m had already been spent on the administration process.

"The amount of money being spent on Metronet's administration is just throwing more money down the drain," said Mr Crow.

"It is an expensive charade. The Government should end the uncertainty and allow London's Mayor to bring Metronet contracts back into the public sector."

But a spokesman for TfL said: "The collapse of Metronet will have no impact on preparations for the Olympics."

He added: "Nonetheless it is in the best interests of all parties for an exit from administration as quickly as possible.