The Liberal Democrats may drop their long held opposition to any airport expansion in south-east, leader Nick Clegg indicated yesterday.

The deputy prime minister suggested that he had been persuaded by some of the arguments laid out in Sir Howard Davies’s Airports Commission interim report for a second runway at Gatwick.

In their election manifesto in 2010 the Lib Dems promised to “cancel any plans for the third runway at Heathrow and any expansion of other airports in the south-east.”

But discussing this section of the report on his regular call in radio slot on LBC Radio, Clegg said: “I am the sort of person who generally tries to be led by the evidence … In his interim report he [Davies] actually makes some quite subtle arguments.

“If you are in favour of airport expansion you then have to decide why you are doing it. Some people say you need to do it to create a hub. That is what the people around Heathrow say – they say, oh it is the hub, the hub.

“Actually he says there is quite a strong case to say real growth in aviation will be these point to point flights – not hub flights where you need connections to ongoing flights. That is the case for Gatwick.

“Where I am very rigid is on the environmental tests in of this. That is why I have been sceptical. I don’t like the idea of turning our back on our climate change commitments.”

Clegg stood by his previous criticisms of Heathrow and said he would not endorse any plan which would increase the existing levels of noise and air pollution but did not specifically rule out a second runway at Gatwick, the Telegraph reported.

He said London mayor Boris Johnson’s idea for an island airport would not “remotely” pass the environmental tests that his party would require.

Business secretary Vince Cable said any expansion of Heathrow would allow London to become a “giant suction machine” draining the life out of the rest of the country.

Cable, whose constituency of Twickenham is under the airport’s flight path told BBC Radio Four’s Today programme that smaller regional airports across the country should be better used to increase capacity.

However, he admitted the Davies report recommending expansion was “very well argued.” Johnson called Cable “stupefying and ridiculous” for suggesting London is a drain on the rest of the UK.