After the longest planning inquiry in British history, the Transport Secretary, Mr Stephen Byers, yesterday approved the £2.5 billion fifth terminal at Heathrow airport, creating more than 6,000 jobs.
However as Mr Byers stressed the new terminal, known as T5, was "in the national interest", Friends of the Earth condemned the decision as a "blow to people's health and the environment".
Confirming the British government's decision after a four-year public consultation exercise which ended in 1999, Mr Byers told the Commons T5 would enable Heathrow to remain "a world class airport" at a time when the London terminal was facing strong competition from European cities such as Paris, Frankfurt and Amsterdam.
The three cities expanded their airports during the planning inquiry and the British Airport Authority (BAA), owners and operators of Heathrow, and unions had lobbied the government to secure Heathrow's position as the key European transport hub.
The government's decision, which was welcomed by airline unions as a "jobs bonanza" for London and the south-east, means 6,500 jobs at the new terminal will be created and 10,000 existing jobs will be guaranteed.
The new terminal can also expect to handle up to 30 million extra passengers a year, many of whom may be passengers travelling between Britain and the Republic. T5 will open by 2007.
Mr Gerry Feeney, managing director of Tara Travel, one of the largest travel operators in Britain dealing with the British-Irish market, said approval for T5 "has to be good for the client" and low-cost airlines.
"From our point of view anything that increases the volume of traffic would lead to a significant increase in passengers and we have to say well done to that decision," he told The Irish Times.
In response to opposition from environmental groups and some residents living close to the proposed terminal, Mr Byers said his approval came with conditions on noise levels, the number of flights and the improvement of public transport links to cut pollution.
Mr Byers capped flights at Heathrow at 480,000 a year, an increase of only 20,000 on the current figure. He said T5 would not go ahead until the Piccadilly Tube line and Heathrow Express train services were extended to serve the new terminal.
The government is also expected to observe last month's European Court of Human Rights ruling that night flights violated the rights of residents living underneath the airport's flight paths.
Friends of the Earth said millions of people would find their lives "blighted" by T5. A spokesman for the environmental group said: "The conditions announced don't add up to a row of beans."