The London Chamber of Commerce and Industry has said the prospect of Brexit means the expansion of both Gatwick and Heathrow is an “absolute priority”.
It also said the overwhelming number of Londoners who voted to remain in the EU meant the capital should have more control over its finances.
While the chamber did not campaign for either side in the referendum, a survey of its members in May showed 63% were in favour of remaining, 36% Leaving and 2% were undecided.
Chief executive Colin Stanbridge said Brexit meant London must now ensure it had the business environment, strategic infrastructure and skilled staff to attract global companies to invest and locate in the capital.
Read more: More reaction to Brexit here
He believes ministers needs to develop a national strategy for exports and growth to coordinate departmental activity and ensure UK businesses are given the support needed to trade overseas.
He said: “The Government must look to maintain the capital’s position as world-leading place to do business.”
The chamber has long been an exponent of building new runways at both Heathrow and Gatwick, in a staggered approach, as it said developing only one airport was “short-termist madness”.
Colin said aviation capacity to connect to “far-off key markets” should now be a key part of the Government’s strategy.
He said: “International trade has long been a critical component of Britain’s economic well-being.
“Now more than ever there is a pressing need to encourage and support British businesses to engage in international commerce and help build a strong and prosperous UK economy.
“It is now an absolute priority that ministers take a decision on expanding both Heathrow and Gatwick.”
He also stressed it was vital Mayor of London Sadiq Khan was involved in planning for Brexit as the economic burden of paving the way ahead would fall most heavily on the capital.
In the wake of the referendum result the chamber also called for London to be given more control over its finances as it said the Mayor had control over 7% of taxes raised within the capital in comparison to equivalent politicians in New York and Tokyo who controlled 50% and 70% of local tax revenues respectively.
Colin said:“In our greatly changed political landscape our Mayor’s weak fiscal position cannot continue.
“The 2013 London Finance Commission called for Westminster to increase London control of local tax revenue from 7% to around 13%.
“Hardly a revolutionary request but enough to begin making a noticeable difference in what and how the Mayor could advance enhancements in key infrastructure like transport, housing or broadband.
“Additional revenue could help boost Mayoral efforts to project London’s presence on the international stage with more overseas trade missions to forge new trade links and attract inward investment.”