Tory leader David Cameron has launched an outright attack on plans to expand Heathrow.

Writing in last night's Evening Standard Mr Cameron said the "economic case for Heathrow expansion is unravelling day by day."

And he accused Prime Minister Gordon Brown of being driven by "political calculation, not conviction" in his desire to back a bigger Heathrow.

Mr Cameron's open assault on the Government's proposals to expand Heathrow has been welcomed by campaigners.

Chairman of Hacan John Stewart said: "It is particularly significant that he is questioning the economic case for expansion.

"The noose is tightening round the Government's neck, slowly draining their proposals of any purpose. They should abandon them."

Mary Macleod, Conservative parliamentary candidate for Brentford and Isleworth, said: "I welcome David Cameron challenging Gordon Brown on this issue and questioning the economic argument for expansion.

"I do not believe that the economic argument stands up and businessmen like Bob Ayling, former CEO of British Airways, does not either.

"Instead, the increase in number of flights brings with it issues of noise, safety, security, traffic congestion, health and pollution for local people. I want to make life better for residents, not worse, and therefore will fight this to the end.

Councillor Barbara Reid, Hounslow's lead member for the environment, said: "David Cameron has shot a hole right through the Government's economic case for Heathrow."

Council leader Councillor Peter Thompson said: "Opposition to Heathrow expansion is massive and growing. David Cameron's comments are timely and welcome. Expansion fails both the environmental and economic case and the Government should abandon its plans right now."