Transport Secretary Geoff Hoon has announced government approval for a third runway at London's Heathrow Airport. The plan is for a new 7,200ft runway, allowing the annual number of take-offs and landings to increase to 605,000 by 2020 and 720,000 by 2030 - up from 480,000 today. A new terminal, capable of handling 35 million passengers per year, would serve long and short-haul services. A new tunnel would allow the A4 to pass under taxiways between the airport and the new runway. The M4 spur to the airport would also have to be moved and hard shoulders on the most congested motorways would be opened up to be used during peak times.

There is no firm commitment but the government says it is setting up a company to look into new high-speed rail services between London and Scotland - with a new line between London and the West Midlands. Transport Secretary Geoff Hoon says there is a "strong case" for the new line to get to London "via a Heathrow International hub station on the Great Western line, to provide a direct four way interchange between the airport, the new north-south line, existing Great Western rail services and Crossrail into the heart of London".

Many environmental groups and residents who live around the airport are strongly opposed to further expansion due to fears about increased noise and air pollution and congestion. The Conservatives and Liberal Democrats also oppose the third runway and the government faces a backbench rebellion, last year 40 Labour MPs backed calls to put it to a Commons vote - they said the government relied too much on data from Heathrow owner BAA in assessing the case for expansion. The Conservative mayor of London, Boris Johnson, also opposes it.

The Future Heathrow pro-expansion group, made up of businesses, trade unions and aviation firms, says a third runway is vital for trade and tourism, and to secure the future of an airport employing 72,000 people. Business groups fear Heathrow is losing ground to rival European airports in Paris, Frankfurt and Amsterdam which will each have four runways by 2012.

Green campaigners have been backed by the Environment Agency, which said a new runway would fail EU pollution limits because of unsafe nitrogen dioxide levels. Groups such as the Heathrow Association for the Control of Aircraft Noise (HACAN) and the No Third Runway Action Group have protested against the proposal on the grounds of excessive noise and because it will destroy communities.

The 2M group, an alliance of 12 local authorities, claims the economic benefits are overstated and the environmental costs ignored. It says carbon emissions will double by 2050 if the government's assumptions about the development of new, environmentally-friendly aircraft prove incorrect.

The government says there will be an initial cap on extra flights to about half of the original proposal - 120,000 a year, rather than the 220,000 originally envisaged. It also says only the cleanest planes will be allowed to use the new runway. And it says there will be a new aviation emissions target - that levels in 2050 will be lower than those of 2005. It admits that nitrogen dioxide levels at Heathrow are higher than the EU limit - which is supposed to come in in 2010 - but says it is likely to ask for an extension to 2015 and says it could be met mainly by reducing car emissions.

Opponents say hundreds of thousands of homes will be exposed to more noise from planned new flight paths. The government had already committed not to enlarge the area in which average noise exceeded 57 decibels - the level considered an irritation. It says this can be done, even with a third runway, because newer aircraft are quieter and will get priority. It insists no extra flights will be allowed until the Civil Aviation Authority is satisfied noise and air quality conditions have been met and will not be breached. The CAA will also have a legal duty to take "action needed to come back into compliance" if limits are breached.

Following the announcement of the U.K. Government decision to add a third runway at London Heathrow, International Air Transport Association Director General and CEO Giovanni Bisignani issued the following statement:

“The U.K. Government made the right decision. The third runway allows Heathrow to grow, and, more importantly, it will be an enormous economic catalyst by better connecting the London and U.K. economies to global business,” said Bisignani.

“Growth must be environmentally responsible. The environmental restrictions on the third runway are challenging,” said Bisignani. “IATA’s four-pillar strategy on climate change - focused on improved technology, effective operations, efficient infrastructure and positive economic measures - is delivering real results. Since 2004 we saved over 59 million tonnes of CO2. Moreover, as a result of the efficiencies that our industry continues to put in place, we have limited our CO2 emissions to 2% of the global total. Our track record is impressive. And no industry is as ambitious about its future. I am confident that the environmental impact of the third runway can be managed effectively,” said Bisignani.