A report published on Wednesday by the capital's connectivity commission -- formed by London First -- said all viable options for meeting the UK's long-term need for further airport capacity, including a new airport, should be considered.

However, it added that the British government, which last month announced plans to hold a formal consultation on proposals for a Thames estuary hub, dubbed Boris Island after London Mayor Boris Johnson, criticised the government for ruling out a third runway at Heathrow for political reasons.

"Rather than kicking politically difficult solutions into the long grass, it should consider all options and look at what is best for the UK's prosperity," Jo Valentine, the chief executive of London First said on Wednesday.

"It could be viewed as negligent of government to make such an important decision on purely political grounds. A third runway at Heathrow should be ruled back into the options."

The commission led by Peter Robinson, who is chairman of law firm Berwin Leighton Paisner, said a new hub airport was the type of long-term infrastructure planning London needed to remain competitive.

But it warned that a new airport could take up to 30 years to deliver and would be unable to meet the urgent need for new hub capacity that London currently faces.

The report said the absence of spare capacity constrained London's ability to offer a significant range of long-haul routes to growing markets in Asia and Latin America, putting the British capital at a competitive disadvantage to cities in Germany, France and Holland.

"Without urgent action to meet this need, government runs the risk that investment decisions being taken both by businesses in growing economies and by the airlines that serve them will be difficult, if not impossible, to reverse," said the report, adding that proposals for new hub capacity should be assessed only if that can be delivered in the next 15 years, given the urgent need to tackle the consequences of Heathrow's over-utilised capacity.

The report recommended that in the meantime Ferrovial-owned Heathrow (FER.MC) should have greater freedom to operate more efficiently by allowing planes to land and take off concurrently on both runways. It said freedom to operate in this way could increase runway capacity by up to 15 percent.

If this option was given the go-ahead, the government should commission advice from the regulator on ways to minimise the distribution of noise from different flight patterns, it said.

The commission said expanding capacity at Gatwick, London's second largest airport, and improving transport links between Gatwick and Heathrow would not provide an adequate solution.

(Editing by Will Waterman)

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