The Leave vote in the EU referendum means it is "clearer than ever" that Gatwick should be expanded, according to the airport's boss.

Stewart Wingate, chief executive of the West Sussex airport, will claim in a speech that the project would "give the country certainty of delivery".

It was previously suggested that the Government could announce a decision on whether to expand Heathrow or Gatwick next month, but David Cameron's resignation could mean a further hold-up in the much delayed process.

Mr Wingate is expected to say: "It is now clearer than ever that only Gatwick can deliver the new runway Britain needs - to provide the direct connections to North America, South America, Europe, the Middle East and Asia that we all want, because only Gatwick can balance the economy and the environment.

"In these uncertain times, that means Gatwick can give the country certainty of delivery. And Britain cannot afford yet more delay."

He will tell the National Infrastructure Forum's annual conference on Tuesday that a second runway at Gatwick can be delivered by 2025 "at a fraction of the environmental impact" of expanding Heathrow.

"Momentum has been growing behind Gatwick over recent years," Mr Wingate will claim. "The time has now come for everyone to get behind a new runway so the country can get the economic boost that is more important than ever. And that can only mean Gatwick."

But Heathrow chief executive John Holland-Kaye has insisted that people across Britain are counting on the Government to give the go ahead for a third runway at the west London hub. He said the plan has support from around two-thirds of MPs.

''At an uncertain time for the British economy, MPs recognise that Heathrow is a private sector infrastructure project that will spread growth across Britain from the moment that we get a green light.

''Now more than ever, people across Britain are counting on the Government to take bold decisions that show we are a confident outward looking trading nation," he said.

John Stewart, chairman of anti-Heathrow expansion group Hacan, believes the referendum result "must cast doubt" on whether the airport will ever be granted permission to build a new runway.

"The Prime Minister and the Chancellor have lost the fight of their lives," he said.

"Outers like Boris Johnson, who is fiercely opposed to Heathrow expansion, have won. At the very least, a decision on a new runway must now be up in the air."

He added: "The Government had pencilled in 7th or 8th July to announce its runway decision.

"It may confirm its intentions over the next few days but it would be surprising if a lame-duck Prime Minister risked further splits within the Conservative Party by making such a controversial decision just weeks before he leaves office."