Labour MP Alan Keen has vowed to continue fighting expansion at Heathrow, even if it costs him his seat at the next election.

Mr Keen who represents Feltham and Heston, is one of 105 MPs who have put their name to an early day motion calling on the Government 'to rethink its plans for a third runway at Heathrow Airport and to give full consideration to alternative solutions'.

But he admits his position may not be popular with everyone in the west of the borough.

He said: "I'm aware that my constituents have mixed feelings about the airport despite the noise. Obviously, a lot of people work at Heathrow or have family members working there.

"If I listened to BAA they'd suggest I could be risking my seat and certainly I've nothing to gain from this. But I feel  strongly that further expansion, and particularly an end to runway alternation, would be harmful to my constituents."

Mr Keen says he is optimistic about the campaign to limit expansion and pleased that he and his fellow campaigners managed to get a meeting with Gordon Brown to discuss the subject last week.

He added: "Unfortunately, the Prime Minister was called away before we could finish the conversation but we are due to meet again in the near future. I can't really talk about what was discussed but I am very pleased we are being listened to."

The number of Labour MPs backing the early day motion has led the campaign group HACAN to suggest the Government would be unlikely to get the support of Parliament if its plans to build a third runway at Heathrow were put to a vote of all MPs.

Forty Labour MPs have signed the motion and if they joined forces with opposition MPs the Government would almost certainly lose any vote in the commons.

Mr Keen's wife Ann, MP for Brentford & Isleworth, is prohibited from signing the motion as a government minister but has been vocal in her opposition to expansion.

HACAN chairman John Stewart said: "The expansion plans do not need to be voted on but we are calling on the Government to have the courage to put its proposals before Parliament before taking any decision."