The government is being urged by airlines to force Heathrow to promise not to raise passenger charges before approving plans to build a new runway.

Heathrow has pledged to keep down costs but the bosses of British Airways owner International Airlines Group and Virgin Atlantic want the government to demand a guarantee that the airport would not become more expensive as it expands.

“They (Heathrow) should give the commitment that they’ve so far refused to give which is a guarantee that passenger charges will not increase,” IAG CEO Willie Walsh told the Commons Transport Select Committee yesterday.

He warned that if building the new runway and associated terminals and new infrastructure gets too expensive, the expansion will not bring the extra flights that the government hopes will boost trade and the economy.

“You won’t get additional flights if Heathrow becomes even more expensive,” he said.

Virgin Atlantic chief executive Craig Kreeger called for Heathrow to provide a “passenger cost guarantee” to incentivise the airport to stick to its spending plan.

He said: “We find ourselves in a position where our endorsement is sought for a plan where the consequence of an overspend will be borne by the airline and its customers.

“They have the most information on how likely the costs are to be deliverable – and they should bear the risks of their estimate being grossly, grossly off target.”

EasyJet UK director Sophie Dekkers said the airline welcomed that  transport secretary Chris Grayling and Heathrow had said the charges would be as close as possible to current levels but “we would want a commitment”.

Walsh has called for competition to be brought in at Heathrow with third parties allowed to develop and run terminals.

Heathrow said in December it could shave £2.5 billion off the original bill, bringing it down to £14 billion.

The airport’s chairman Lord Paul Deighton yesterday pledged to maintain airline charges “as close to current levels as possible” when a third runway is built.

The heads of IAG, Virgin Atlantic and easyJet were joined by Baruk chief executive Dale Keller and Civil Aviation Authority chief executive Andrew Haines in giving evidence to the Transport Committee’s inquiry into the draft Airports National Policy Statement.

Grayling has said that the government aims to give the formal go-ahead to a new runway at Heathrow in the first half of 2018 subject to consultation work and securing the backing of parliament.