A third runway at Heathrow will be built, transport secretary Geoff Hoon confirmed this afternoon.

The option of a longer runway was chosen out of several possibilities open to the Government after a much-criticised consultation last year, with the international business success of the nation cited as the overriding concern.

The number of extra planes using the airport, expected to be ready in 2019, will be limited initially to 125,000 instead of the 220,000 capacity, and extended powers are to be bestowed on the Civil Aviation Authority to police environmental limits, particularly of greenhouse gas nitrogen oxide.

Plans for mixed-mode use of the runways will be scrapped, but so will the Cranford Agreement which currently protects the residents from extra noise pollution.

Claiming that 'Doing nothing will damage our economy and have no impact whatsoever on climate change', the transport minister announced that the UK is unlikely to meet current EU targets of climate change by 2010 and pointed to the 'significant challenge' of extended targets for 2015 as the changed goal posts, a move sure to infuriate anti-expansion campaigners.

He also used evidence compiled to show a 68% reduction in the numbers of people expected to suffer from noise above 66 decibels as new engines come into use as justification for the increase in flights and immediate increase in the numbers of people likely to suffer above 57 decibels of noise on a regular basis such as those living in Feltham.

Millions of pounds of investment into the motorway network and the electrification of large parts of the train network were also announced.

Christine Shilling, of No Third Runway Action Group (NoTRAG), said the Government had ignored the views of 70,000 people who took part in the consultation process last year and vowed to continue campaigning until the 'bitter end'.

"This is not the end," she added. "It is simply the end of the beginning."

Hounslow Council revealed today how its survey of 2,000 west London residents showed a massive 96 per cent were opposed to expansion.

Cllr Barbara Reid, the council’s aviation chief, said the Government should 'realise it is beaten and give up'.

She added that the council was likely to launch a legal challenge, backed by London Mayor Boris Johnson, on the grounds Heathrow is already breaching a raft of guidelines on pollution and noise.

Activists, who have spent the last few months training in militant camps, are also expected to step up their campaign of direct action.