MP Cheryl Gillan has called for a full injury into HS2 Ltd’s dealings with its former contractor and said to the Commons “billions of pounds of taxpayers money is at stake”.

The MP, who represents Chesham and Amersham , aired her concerns to the Transport Secretary on Thursday (March 30) about CH2M’s relationship with HS2 Ltd.

CH2M was contracted as HS2's Phase 2b delivery partner earlier this year – a decision which prompted rival bidder Mace to threaten legal action against the company.

The planned route for HS2

Mace accused the two of having a “revolving door recruitment policy” after a number of HS2 Ltd staff, including then CEO Roy Hill, were on secondment from CH2M.

Now, CH2M have surrendered its £170million contract.

The MP from Bucks was joined by others when she asked for an official inquiry into their dealings during transport questions.

Mrs Gillan said: “This announcement about the contract illustrates that there needs to be total transparency by HS2 Ltd.

“Concerns like this have been brushed aside and what happened this week shows that there is a need for rigorous scrutiny.”

The MP then insisted that “there should be no further contracts before a full inquiry can be conducted into the decision-making process”.

Mrs Gillan also asked the Leader of the House David Lidington, MP for Aylesbury, to make time in the Commons so that there could be “an urgent debate on conflicts of interest”.

Joe Rukin, the campaign manager for Stop HS2, similarly called for contracts to be scrutinised.

He said: “With the next set of contracts running into the billions, we call on the government to immediately investigate the award of all HS2 contracts.”

Stop HS2 campaigners have been protesting against the railway since 2009

HS2 released a statement after CH2M dropped out of the contract and said: "As they have announced, CH2M have decided to withdraw from the Phase 2b Development Partner bid process, a decision which we welcome.”