Global airlines body IATA said on Thursday it has agreed new rules on the way fuel is rationed at London's Heathrow Airport after an oil depot explosion knocked out a third of the airport's supplies.

IATA said it brokered a voluntary fuel allocation deal between airlines and airport operator BAA after some airlines complained the previous system discriminated against non-UK carriers.

The new deal would eliminate the need for some airlines on long-haul flights to make extra stops at nearby airports to refuel. Airlines would continue to be treated differently on short-haul flights, IATA said.

"The fuel crisis at Heathrow is unprecedented. Today's agreement is a pragmatic solution to a very difficult, complex and unique situation," IATA Chief Executive Giovanni Bisignani said in a statement.

Carriers from the United States, Asia, South Africa and elsewhere have been forced to tanker in large amounts of fuel or to re-fuel at other airports since a fire at the Buncefield Fuel Depot in December cut the airport's fuel supplies by 35 percent.

The US State Department last week complained to Britain, alleging that American Airlines and United Airlines were being unfairly penalized by the system. They are the only two US-based airlines permitted by treaty to use Heathrow.

London-based airlines British Airways, Richard Branson's Virgin Atlantic Airways and bmi were allocated a greater share of fuel than other airlines using the airport under the previous system.

IATA said the new agreement would take effect on February 20, but warned it still needed to find a solution to accommodate busy summer schedules starting in April.

American this week introduced a GBP