A decision on whether to build a controversial third runway at Heathrow Airport will be delayed until after the election of a new Conservative party leader. Prime Minister David Cameron was due to make a decision imminently and was widely expected to approve the new runway to alleviate the pressures on the UK's air capacity.

But his decision to step down after the Brexit vote in the 23 June referendum has thrown the decision into doubt. The favourite to succeed Cameron as leader of the Conservatives and so prime minister of the country — Theresa May — is an opponent of a third runway at Heathrow.

The final decision on the runway will now not take place until "at least October", the transport secretary Patrick McLoughlin told the House of Commons, which will be after the party's leadership election. A new leader will be in place by 9 September.

Options to expand the UK's air capacity were considered by the Airports Commission, led by Sir Howard Davies, including another runway at Gatwick or an entirely new airport for London. It recommended a third runway at Heathrow as the best option, infuriating local campaigners who oppose it primarily on environmental and noise pollution grounds.

"If Britain wants to be confident, outward-looking and at the centre of the world's economy then expanding Heathrow must be a key building block in the government's Brexit plan," said John Holland-Kaye, Heathrow's chief executive.

"It will allow British exporters to trade with all the growing markets of the world, strengthening Britain's position as one of the great trading nations. And at a time of uncertainty a £16bn ($22bn) privately funded infrastructure investment will create jobs and growth across the UK. Government can send the strongest possible signal that Britain is open for business and confident in its future by expanding Heathrow."

"Today's announcement means residents face further uncertainty over the future of the local area," said Robert Barnstone, campaign coordinator of Stop Heathrow Expansion. "Whilst it is only a short delay, many residents have experienced blight for many years and would now like and answer.

"We will watch the Conservative leadership contest very closely over the coming weeks and look forward to listening to all the candidates' views. They are very welcome to visit the area to see what's at stake."