Transport Secretary Patrick McLoughlin said it was important the "best people" worked on the HS2 project after it emerged more than 30 staff on the £50 billion scheme could be better paid than the Prime Minister.

The high-speed rail scheme firm's boss Sir David Higgins suggested "at least" 20 or 30 staff could be hired in the next six months with pay levels above David Cameron's £142,500 salary.

Mr McLoughlin said the proposed salaries were "within the budget we've set" but would have to be approved by the Treasury.

The Transport Secretary said he had spoken to Sir David about senior salaries, telling BBC Radio Derby: "It has to go through a procedure, I have to get clearance from the Treasury and that will be done.

"I'm OK with that."

He said: "These people are not civil servants, they are engineers at the height of their skills who would be paid a lot more in the private sector."

Mr McLoughlin added: "I hope we find the best people for this project. It's a very important project."

Sir David told BBC2's Newsnight: "The worst money you can save is skimping on hiring the best people. I am determined that we hire the best people.

"We are not going to pay over the odds, we probably won't even pay what the private sector would pay."

He added: "We have to have the flexibility to hire the right people now rather than when something gets into a problem in years to come."

Sir David said the staff would be held accountable for their performance and "if they don't perform they'll go".

"They won't be on long-term government pensions or long-term tenure," he said.

"At a senior level, you are talking about people above the Prime Minister's salary, in the next six months we need to hire 20 or 30 of those at least to do a project of this size."

A spokeswoman for the Prime Minister confirmed the Treasury would have to sign off any decisions on hiring senior staff and added: "This is a vital infrastructure project and of course it is important that we have the right people running and working on that project in order to deliver it on time and on budget and at good value for the taxpayer."