Heathrow’s claims it will not increase landing charges to pay for a new runway are not credible, according to former British Airways chef executive Sir Rod Eddington.

The Australian businessmen is leading a group advising hotel magnate Surinder Arora, who has come up with an alternative scheme to Heathrow’s own third runway plan.

Arora claims his plan will cost up to £7 billion less than Heathrow’s, which is costed at £17.5 billion.

Sir Rod, one of the world’s most experienced airline bosses having run Ansett, Cathay Pacific and BA, told the BBC it was “very difficult to see how that is possible, and more importantly, the airlines themselves do not believe that it is.”

He said the Arora plan had sprung out of concerns that airlines and other businesses at Heathrow had with the airport’s own scheme.

“They are concerned about the costs,” said Sir Rod.

The full savings that could be achieved would depend on final decisions on the orientation and length of the new runway, but significant costs could be taken out in the construction of a new terminal and how the existing terminals were adapted, he added.

“We can’t gild the lily – we need a new runway, but if it’s not affordable, it runs the risk of driving business away from Heathrow, not attracting it.”

Heathrow said it had shared its plans with airlines “at every step”.

“While the Arora plan may appear to reduce financial costs, it was in essence, rejected by the Airports Commission because of the significant environmental burdens it would impose on many,” the airport operator said.

“We remain 100% committed to delivering expansion affordably – but we will not compromise on commitments made to local communities.”

Heathrow chief executive John Holland-Kaye earlier branded as “categorically untrue” a Sunday Times report which implied that the airport wants to double airport charges with expansion through a third runway.