Heathrow’s controversial proposal to build a third runway would place a £16bn burden on Transport for London, the agency has said, as it would require upgrades to the road and railway networks that service the airport.

TfL said Heathrow had “substantially underestimated” the impact of the extra runway, as it released a figure eight times higher than the £2.2bn that the airport had calculated.

The transport authority instead estimates that the development, which could lead to heavier congestion on London's roads, buses and trains, will have a £18.4bn price tag.

Heathrow has previously promised that £1.2bn would be raised through public contributions, with the airport spending another £1bn, leaving a shortfall of more than £16bn.

TfL is not the first organisation to claim that Heathrow has underestimated the cost of building the controversial third runway. The long-awaited Airports Commission Report revealed that the runway would cost £18.6bn, £3bn more than the airport suggested.

Heathrow is in the midst of a head-to-head battle with Gatwick Airport for expansion. After failing to make a decision on Heathrow expansion by last Christmas, the UK Government is now expected to wait until after the European referendum in June.