Prime Minister Andy Burnham refuses to take stance on Heathrow third runway expansion

Prime Minister Andy Burnham has refused to say whether he backs a third runway at Heathrow after it emerged that the expansion of the London airport could be delayed by up to four years.

Burnham - who, as Mayor of Greater Manchester, opposed the project - told Sunday With Laura Kuenssberg: "I think principally, it's a matter for London and Londoners."

He added: "I think we ought to hear the voice of people there first. It's not right for me to just jump straight in on the back of the consultation."

Former Chancellor Rachel Reeves had championed the runway to boost the economy, with a schedule to open by 2035 but Heathrow indicated on Saturday it may not be operational before 2039.

As Manchester's mayor, Burnham had been against the project over concerns that it would delay investment in transport for the north. When he took office, he said he was "open-minded" about the scheme.

As he prepared for his first annual Labour Party conference as prime minister, Burnham said: "There's a consultion but there are different views and you have to take those views seriously in coming to a decision."

In response, Heathrow said: "We agree with the prime minister that local voices must be heard. We know from consistent polling over the last decade that communities support our plans for expansion and support is only growing over time."

The project, estimated to cost £33bn, has attracted opposition from environmental campaigners and local resident groups as well as Mayor of London Sadiq Khan.

A third runway would mean demolishing hundreds of homes, diverting rivers and rerouting a section of the M25 motorway through a tunnel.

But it is estimated it would create 100,000 jobs and provide a major boost to the UK economy.

The number of flights from the site, currently capped at 480,000 a year, could go up to 720,000, or nearly 2,000 a day on average.

A new runway has been backed by the unions Unite and the GMB.

Sharon Graham, Unite's general secretary said: "A third runway at Heathrow is essential and we need to get going with it."

"This is more than just infrastructure. It's about investing in the workforce, securing the future of good, unionised jobs and a guaranteed market for UK steel."

Earlier this weekend, Heathrow conceded that meeting the original deadline would be increasingly difficult without further steps to simplify the planning process.

It said it hoped to secure planning permission by 2029 and then open the runway "within a decade".

The Department for Transport said the timeline had "always been ambitious" and it would continue to work with stakeholders "at pace" on the matter.