Transport Secretary Patrick McLoughlin is expected to appear before MPs tomorrow when the Commons returns to explain the costly and embarrassing U-turn over the award of a new franchise.
He has already announced a review of the "unacceptable mistakes" by officials that led to the tendering process being restarted.
But Shadow Transport Secretary Maria Eagle said it was unacceptable the probe would be headed by non-executive directors of the Department for Transport and accused ministers of pre-judging the outcome.
The true cost of the fiasco over the West Coast Main Line franchise is only just beginning to become clear.
A critical report by MPS has condemned the £50 million cost to the taxpayer caused by the West Coast Mainline fiasco.
Transport Secretary and Derbyshire Dales MP Patrick McLoughlin has told MPs today that mistakes over West Coast should not have been made.