(Agencies)
Updated: 2008-03-14 09:26

LONDON -- Queen Elizabeth II is to unveil a new terminal at London's Heathrow airport Friday, under tight security a day after a major scare sparked by a man running on to a runway.

Terminal Five (T5) will increase Heathrow's capacity by 30 million passengers a year, but comes as campaigners step up protests over plans to expand the airport.

Planes at London's Heathrow Airport. Queen Elizabeth II is to unveil a new terminal at London's Heathrow airport Friday, under tight security a day after a major scare sparked by a man running on to a runway. [Agencies]

It was unclear if Thursday's alert, in which a man scaled a perimeter fence and ran on to the north runway, was designed as a protest. Police carried out a controlled explosion of two bags dropped by the man.

But security will be tight for Friday's ceremony with the queen, after threats by the campaigners to stage a new demonstration timed with the terminal's opening.

Construction of Terminal Five (T5), which will open for flights on March 27, has taken nearly six years and cost some 4.3 billion pounds (8.7 billion dollars, 5.6 billion euros).

The new building has involved the construction of 13 miles (21 kilometres) of tunnels, 10 miles of baggage conveyor belts, and the extension of the Piccadilly Tube line to transport passengers to and from central London.

"It will breathe new life into Heathrow, allowing us to continue our transformation of the rest of the airport," said Nigel Rudd, chairman of the British Airports Authority (BAA).

Located west of London, Heathrow is already one of the world's biggest airports, but has for years been plagued by overcrowding due to ever-expanding demand for air travel.

The extra capacity will increase the overall number of passengers using Heathrow by nearly 50 percent, from more than 68 million to some 100 million a year. The new terminal will be used solely by British Airways flights.

But protestors have recently stepped up a campaign against a third runway at the airport, which they say will damage the environment and add to misery for local residents, after signs that the British government backs the plans.

Demonstrators have warned they will protest when the new terminal opens later this month, but airport boss Mark Bullock said, "We will be ready for them" with contingency plans in place for any such demos.

Activists from environmental campaigners Greenpeace breached security at Heathrow last month to stage a demonstration on top of a jet against the planned new runway.

Three days later, protestors from a group called Plane Stupid made headlines when they managed to get on to the top of the House of Commons.

Another group, No Third Runway Action Group (NOTRAG), says it plans "flash mob" protests at the March 27 opening, according to their website.

Airline bosses say the new terminal, which covers an area roughly the size of London's Hyde Park at the western edge of the sprawling airport site, is essential to cope with rising demand.

"With the opening of T5, BA and BAA have an opportunity to make air travel, both into and out of the UK, once again a calmer and much more enjoyable experience," said British Airways boss Willie Walsh.

The queen's visit to Heathrow comes more than 50 years after she opened the first passenger terminal there in 1955, and 15 years after BAA first made a planning application for the new facility.