Conservatives have called for an investigation by Whitehall's spending watchdog into public-private partnerships on London's Tube system, in the wake of this week's financial crisis at Metronet.
The consortium, which was responsible for maintenance and renewal of two-thirds of the London Underground network, went into administration on Wednesday after failing to secure £550 million to fill a black hole in its finances.
Shadow transport secretary Theresa Villiers said the collapse of the Metronet PPP was a "personal failure" for Prime Minister Gordon Brown, who pushed the public private partnerships through in the face of stiff opposition when Chancellor.
She wrote to Auditor General Sir John Bourn to call for a National Audit Office (NAO) investigation into the operation of the PPP contracts.
Ms Villiers said: "The unfolding crisis at Metronet is a personal failure for Gordon Brown. He forced this flawed PPP on London in the teeth of strong opposition from the capital.
"He received many warnings at the time of the problems that the structure would involve, yet he disregarded them all, despite the fact that there were a range of other options that could have been considered. Now the chickens are really coming home to roost.
"I believe it is time for the NAO to investigate just how badly wrong things have gone under PPP.
"During their first investigation of PPP, the NAO highlighted that nearly half a billion had been spent on consultancy fees. I fear that their conclusions could be just as worrying this time round. It is now vital that lessons are learned from the wind up of Railtrack and that costs are not allowed to escalate as they did disastrously in that case."
Metronet was one of two private companies - the other is Tube Lines - contracted to maintain and renew the Underground in a 30-year PPP plan that was bitterly opposed by London Mayor Ken Livingstone and many others.
Metronet's two contracts cover the Bakerloo, Central, Victoria, Waterloo & City, Circle, District, Hammersmith & City, Metropolitan and East London lines. The consortium wanted London Underground to pay an extra £551 million over the next year to cover some of its cost overruns, but Tube PPP arbiter Chris Bolt ruled earlier this week that Metronet should receive only £121 million.
