LONDON, Sept 1 (Reuters) - A major business lobby group has thrown its weight behind Britain keeping a single hub airport, a position which would favour expansion at London's Heathrow.
The Confederation of British Industry (CBI) said trade growth would be best delivered by a single British hub airport with spare capacity, a view which would suggest growth at Heathrow rather than adding capacity at smaller airport Gatwick, also in the southeast of the country.
"The CBI recommends hub capacity at a single location as the best way of boosting connectivity with new markets," the CBI said in its report, published days before a shortlist of potential new runway sites is finalised.
A government-appointed Airport Commission has been asked to make a final recommendation on where to expand London's airport capacity by summer 2015. It is due to publish a final shortlist early this month.
A recommendation to build an additional runway at Gatwick would represent a move away from the hub airport idea, creating two large airports in the London area.
Heathrow, which by passenger traffic is Britain's busiest airport and the third busiest in the world, is at the centre of a long-running political tussle. Constraints on Heathrow's expansion - it is already 98 percent full - means it is falling behind rival European hubs in the battle for lucrative routes to emerging markets.
British politicians and business leaders want runway expansion, but the idea of adding new capacity near to London is unpopular with many voters because of noise, pollution and safety concerns.
The Commission has already drawn up an initial shortlist, which includes two possibilities for expansion at Heathrow and one at Gatwick.
It will reveal in the coming days whether to add to the list another plan to build a new hub airport from scratch in the Thames estuary which would be bigger than Heathrow and could replace it.
British media reported on Monday that this idea, backed by London mayor Boris Johnson and deemed to be a much more expensive option, was likely to be dismissed by the Commission and not make it on to the shortlist.
A new airport in the Thames estuary would cost between 82 and 112 billion pounds (186.12 billion US dollar), or around five times as much as the other three short-listed options, according to the Commission.
The CBI in its report also urged politicians to put a time frame in place to ensure that building new airport capacity can start in 2020 after years of policy changes and delays. (1 US dollar = 0.6018 British pound) (Reporting by Sarah Young. Editing by Jane Merriman)