The consultation process around the Government's flagship HS2 high-speed rail project, which will run from London to Birmingham, has been questioned after it emerged hundreds of responses were omitted from the original analysis.
Former Conservative Cabinet minister Cheryl Gillan said the £32 billion scheme was in "disarray" and demanded to know if ministers would order a fresh consultation.
The process was branded a "shambles" by one campaign group and the Government was accused of being "complacent" by another as ministers confirmed a "very small proportion" of responses were not fully analysed.
Transport minister Norman Baker said the responses were omitted due to "technical errors" but they would not have changed the outcome of the consultation.
The Government is already committed to going ahead with the first phase of High Speed 2 which would see ultra-fast trains running through Tory heartlands from London to Birmingham on a new line which could be completed by 2026.
The second phase envisages a Y-shaped line continuing north of Birmingham to Manchester and Leeds with connections further north and into Scotland and which would be completed around 2032/33.
The total cost for both phases is estimated at £32 billion but campaigners have warned that it will not provide the economic benefits claimed and will destroy picturesque landscapes.
In a Commons written statement, Mr Baker said further errors in the consultation process had been identified since July when it was announced that more than 400 responses had not been examined by Dialogue by Design (DbyD), the consultants who conducted the analysis.
Mr Baker said: "The cause has been identified as technical errors in transferring data captured from online consultation responses to the consultation analysis database held by DbyD."
But he added: "Inclusion in the original analysis would not have changed the substance of DbyD's findings, nor affected the considerations which informed the decisions following the consultation."
Mrs Gillan, who was sacked as Welsh secretary in David Cameron's Cabinet reshuffle this month, is opposed to HS2, which will run through her Chesham and Amersham constituency.
She said: "The HS2 project is in disarray. How on earth can the public have confidence in the process which has failed even to analyse correctly the original responses to the public consultation?
"I have written to the Department for Transport asking for an explanation and want to know what the contractual position is with Dialogue by Design, whether they will be facing penalties for this shoddy performance and if the Government will now re-run the consultation."