Shadow Chancellor Ed Balls has said the new HS2 chairman will have to prove he has got costs under control when he publishes his report next week.

Mr Balls said HS2 had been “mismanaged” thus far, and he needs to be convinced by a report on Monday by former London Olympics supremo Sir David Higgins that it is cost efficient.

It is thought that Sir David is going to suggest building the high-speed line faster to save money, with a £42 billion bill often being singled out for criticism.

Speaking to the Post, Mr Balls said he will be keen to see the detail.

He said: “The fact is David Cameron and George Osborne have really mismanaged this project.

“They have let the costs get out of control, they have not properly made the case, so we will see what Mr Higgins reports.

“I hope he has got a grip on costs and I hope he is going be able to show that his is a project that will deliver value for money and solve the capacity problems, which are an issue.

“We have always said we want to see this investment go ahead, but I have always said the costs have got to be under control. There is not a blank cheque, and I am hoping that Mr Higgins will produce a good report.”

A report in the Financial Times claims Sir David will recommend a U-turn on plans for Euston station in London.

Plans for Euston were scaled back to last year to cut costs in the face of political controversy over the apparently escalating price tag. The former London Olympics boss is expected to say original plans should be reinstated and funded by private sector developments.

The second phase of the project, from Birmingham to Leeds and Manchester, is currently set to follow on after phase one, the London-Birmingham section, and bringing it forward would mean more legislation through Parliament.

Under the current programme, phase one should be completed in 2026 and phase two in 2033.