A second Heathrow for the south

London will get a second Heathrow under plans for a massive expansion of airports unveiled by the Government today.

Transport Secretary Alistair Darling announced the move in the Commons and warned MPs: "Doing nothing is not an option."

But a huge row with environmental campaigners and residents is certain.

Under the proposals announced by Mr Darling today, either Stansted in Essex or Cliffe in Kent will become an additional major London hub.

Heathrow could also get a third runway, despite claims that its fifth terminal would bring an end to its

expansion. But Gatwick will be spared because ministers are to honour a 1979 agreement ruling out its enlargement.

The building programme, much more extensive than anticipated, is needed to cope with a near trebling of passenger numbers expected in the next 30 years.

Ministers will decide next year where the extra runways will be sited. Wherever they go, they will cost billions of pounds and lead to the destruction of homes and countryside. Environmental campaigners vowed to fight the plans every step of the way.

Mr Darling said that failure to expand London's airports would cost jobs, force air fares higher and bring delays for passengers. The Government expects 300 millionair journeys a year to and from the South-East by 2030, compared with 120 million at present.

Even when Heathrow gets its fifth terminal, already approved, capacity across the region will only be around 150 million journeys per year. A third runway for Heathrow would bring that up to 230 million.

To meet expected demand something more radical is needed.

Stansted appears the most likely candidate for expansion. The number of runways there could be expanded from one to four, overtaking Heathrow as the capital's number one airport.

The alternative is to build a brand new, four-runway airport on marshland at Cliffe, on the north Kent coast. But the £11.5 billion cost could make it an unattractive option.

Construction of a four-runway airport at either Stansted or Cliffe could bring capacity close to the 300 million target without the need for the controversial third runway at Heathrow.

Alternatively, the target could be reached with a new runway at Heathrow and just two extra runways at Stansted.

Mr Darling told MPs: "Where there is increased airport capacity we need to strike the right balance between benefits from increased travel and trade, and their environmental cost.

"Heathrow is already under pressure. Airlines cannot get the runway slots to operate new services. It is already at its limit. Gatwick's single runway is full for much of the day, and Stansted is rapidly filling up too.

"In the meantime, in Europe, there have been substantial developments at Paris, Frankfurt and Amsterdam. All of which want to rival Heathrow. If we do nothing, the UK will lose out."

Further plans outlined by the Government today include a low cost airport for London on the site of a military airfield at Alconbury, in Cambridgeshire.

Villagers near Heathrow have vowed to fight any plans for a new runway or sixth terminal there, saying it would destroy their communities. "We are marshalling the troops," said one protester as hundreds of people packed a meeting last night to voice their opposition. John McDonnell, Labour MP for Hayes and Harlington,

said it would mean demolishing up to 4,000 homes and three schools and removing up to 10,000 residents.

Mr McDonnell said the Government was allowing airport operator BAA to "take the cheap and dirty option of adding runway after runway to existing airports".