Transport Secretary Patrick McLoughlin says he is "OK" with the High Speed Two (HS2) rail project paying senior staff more than the prime minister.
HS2 boss Sir David Higgins revealed he plans to pay as many as 30 people more than the PM's £140,000 salary.
The coalition government has repeatedly said public servants should not get more than David Cameron.
But Mr McLoughlin said the salaries "fell within the budget we've set", but he now had to get Treasury clearance.
Sir David Higgins told BBC Newsnight paying more was "absolutely essential" to get the right people now rather than when problems developed and he would ask for permission to break the rules.
Mr McLoughlin 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. I'm OK with that."
He said Sir David was a "world-renowned engineering expert and has done some incredible public work" and the public servants in question were "engineers at the height of their skills who would be paid a lot more in the private sector".
The first phase of HS2, between London and Birmingham, is due for completion in 2026, with a second Y-shaped section from Birmingham to Manchester and Leeds due to be finished in 2032-33.
The cost of the project in its entirety is estimated at £42.6bn, of which £14.56bn is contingency. A further £7.5bn is needed for the high-speed trains.
However, Sir David refused to guarantee the project would not go over budget.
He said: "I can never guarantee anything personally. What I can do it put in place the decision-making process and the right people to make sure we make the right decisions and we can properly and adequately manage the budget."
Sir David also said the project was about people, not trains.
Fears have been raised that the project will benefit London at the expense of northern towns and cities.
But Sir David said: "It will make more of the North accessible for commuters. It will also facilitate businesses moving north."
The project's chairman said the worst money to save was "skimping on hiring the best people".
He said: "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."
But he added: "We have to have the flexibility to pay the right people now rather than when something gets into a problem in years to come.
"We've got to remember we are hiring project people, project people that will be held accountable for performance. If they don't perform they'll go.
"They won't be on long-term government pensions or long-term tenure, so they will survive on their performance."
He said "at least" 20 to 30 senior staff, who would be paid more than Mr Cameron, would be hired in the next six months.
Earlier this week, MPs began the process of scrutinising nearly 2,000 objections to the HS2 bill.
A committee of six MPs will spend months, perhaps years, listening to evidence from those who will be impacted by the project.
The fate of the scheme will be eventually decided by a vote of all MPs.