Heathrow Airport’s third runway looks “dead in the water” following David Cameron’s resignation, a senior minister has claimed.

Opponents within government want the decision delayed until a new Prime Minister takes over. Front-runner Boris Johnson is a diehard opponent of the third runway plan, while chief rival Theresa May has expressed strong concerns about noise.

The minister told the Evening Standard: “The third runway looks dead in the water. I cannot see either Boris or Theresa approving it, and it would be difficult to attempt to make a decision until the new leader is elected.”

The boss of Gatwick will seize on fears of an economic collapse in a speech this week arguing “the time has come” to unite behind expansion of the second biggest airport. Stewart Wingate will claim: “In these uncertain times Gatwick can give the country certainty of delivery. And Britain cannot afford yet more delay.”

But business leaders appealed to Mr Cameron to push ahead with a decision today. More than 50, including John Allan, chairman of Tesco, and Nigel Wilson, chief executive of Legal & General, signed a letter to The Times arguing that a swift decision would “send a message to the world that Britain remains open for business”.

Gatwick says it could build an extra runway serving the South-East by 2025 at lower cost. But business leaders and a majority of MPs from other regions would prefer to expand Heathrow, saying it would offer better connections.

George Osborne, the most significant minister who pushed for Heathrow expansion, was said to be “wholly occupied” on stabilising the economy in the wake of last week’s Brexit referendum.

There has been speculation that a decision could be delayed by at least four months until the next takes office. The uncertainty comes a full year after the Airports Commission came out for a third runway at Heathrow to solve the capacity crisis holding back the South-East.