Government turmoil in the wake of the vote to exit the European Union is casting serious doubts on a decision over UK airport expansion.

David Cameron was today urged to act swiftly on a new runway in the south-east amid fears over a collapse in economic confidence triggered by the Brexit vote.

Business leaders have told the prime minister to rule on an expansion of Heathrow, pictured, or Gatwick immediately rather than delaying until his successor is in place.

In a letter to The Times today, more than 50 prominent figures, including Tesco chairman John Allan and Nigel Wilson, chief executive of Legal & General, write that a decision on a runway would “send a message to the world that Britain remains open for business”.

Their sentiments come amid claims by Heathrow chief executive John Holland-Kaye that the airport retains the support of large numbers of MPs and with Cameron expected to chair his first cabinet meeting today to plot the government’s response to Brexit.

But the prime minister’s resignation fuelled weekend speculation that a decision on airport capacity will be delayed by at least four months to when a successor is in office.

Cameron had been expected to make an announcement on airport expansion within the next two weeks after more than a year of behind-the-scenes negotiations.

Officials had been set to make the formal recommendation to a senior cabinet committee within days. It was believed the prime minister was going to make the announcement on July 7.

This is now likely to be shelved pending the outcome of the Conservative party’s leadership election.

Heathrow’s chances of expanding are likely to be blocked if former London mayor Boris Johnson becomes the next prime minister because of his opposition to the airport.

The Airports Commission came out in favour of a third runway at Heathrow last July.

It recommended approval of the £17.6 billion scheme over two other shortlisted projects, including a second runway at Gatwick.

Civil servants in the transport department are understood to have endorsed the third runway plan after being won over by new Heathrow promises to curb pollution and noise, including a ban on night flights, The Times reported.