MPs have been told that the independent report into the West Coast rail franchise scandal was altered by the Department for Transport (DfT) before it was published.
The author of the report, businessman Sam Laidlaw, claimed there had been "redactions" by the department, during his evidence session with MPs on 18 December 2012.
He said this had taken place to "remove the identities" of certain civil servants involved in the franchise bidding process.
He also claimed that no proper minutes were taken of a key meeting in the franchise process that saw Sir Richard Branson's rail company Virgin Trains lose its West Coast franchise.
The government scrapped its decision to award the franchise to FirstGroup in October, owing to faulty calculations.
It has already estimated the cost of reimbursing four firms for the cost of their bids would be £40m.
The Laidlaw report found department officials wrongly calculated the amount of risk capital bidders would have to offer to guarantee their franchise proposals.
Transport Secretary Patrick McLoughlin has announced that Virgin Trains would continue running the service until 9 November 2014 when a new long-term franchise would begin.