The Labour Party have claimed that taxpayers could be left with an even-bigger multimillion-pound bill than first feared for the West Coast mainline competition failure.
The line connects London to the West Midlands and the north.
Shadow transport secretary Maria Eagle said train firms might sue for losses suffered when the Government scrapped its decision to award the franchise to First Group.
The company's share price fell 20%, wiping millions off its value.
The West Coast mainline deal has already sparked two inquiries and will cost taxpayers at least £40 million in refunding firms which bid for the contract, and has led to the suspension of three Department for Transport officials.