PM faked the case for third runway claims Cameron

In his most powerful assault on the planned expansion of Britain's premier airport, the Conservative leader charged Gordon Brown with exaggerating economic benefits and betraying the environment.

The Prime Minister's "fetish" for a third runway was driven "by political calculation, not conviction", claimed Mr Cameron in an exclusive article for the Evening Standard.

"With Brown it's always about the politics, not the policy," he claimed. "The Prime Minister has noticed that since I became leader of the Conservative Party, I have pushed the environment higher up the political agenda.

"He sees this as a political threat. So he tries to define the issue of a third runway as a 'tough choice' between the economy and the environment. If you back a third runway you're on the side of jobs, business and prosperity. If you don't, you're somehow not serious, putting lightweight environmental concerns ahead of the economy."

The Conservative leader backed former BA chief Bob Ayling who has dismissed the key economic argument for the expansion plans, which revolve around using Heathrow as a giant hub to attract transfer flights.

Mr Ayling argues the value to the economy from passengers stopping to catch flights to other destinations is minimal - little more than the price of a cup of coffee each in many cases.

Mr Cameron said the chaos when Terminal 5 was opened showed Heathrow's management could not handle an even greater expansion to 700,000 flights by 2030. "I think the whole country can agree that the most important priority for Heathrow is making it better, not bigger," he said.

"That means looking seriously at competition issues surrounding BAA and how our airports are managed."

Mr Cameron's attack on Heathrow's growth may be popular with residents, especially in west London, fearing more noisy flights. But Labour believes the wider public will choose expansion if they think it will mean the era of cheap holiday flights carries on.

The Tory leader's article coincides with a speech to environmentalists in which he will try to reassure hardpressed families that going green need not make them poorer.