Dubai International Airport was the world's busiest for international passenger traffic last year, it said last week, taking that title for the first time from London's Heathrow Airport, which has been running into capacity constraints.

The Dubai airport operator said 70.5 million passengers passed through it last year, up 6.1 per cent from 2013, as the emirate’s trade and tourism industries boomed.

Political unrest in the region has pushed more investors and tourists to Dubai, which is seen as a safe haven, while state-owned Emirates airline and budget carrier Flydubai are expanding rapidly, steering traffic to the emirate.

Heathrow hosted 68.1 million international passengers in 2014, up 1.2 per cent, a Heathrow spokeswoman said.

British politicians and authorities have been wrangling for years over how to increase airport capacity near London but have not reached a decision.

A commission is due to make final proposals by this summer, choosing between three options: a third runway at Heathrow, an extension to an existing Heathrow runway, or a second runway at Gatwick Airport.

“Britain has benefited from being home to the world’s largest port or airport for the past 350 years. But lack of capacity at Heathrow means we have inevitably lost our crown to Dubai,” the Heathrow spokeswoman said.

Dubai Airports, which operates Dubai International, forecast this year’s traffic would jump to 79 million passengers, helped by the planned opening of the new Concourse D, which would boost annual capacity to 90 million.

In December alone, the airport's traffic rose 7.5 per cent from a year earlier to 6.50 million passengers.

Cargo handled by Dubai International totalled 2.37 million tons last year, down 3.4 per cent because of the shift of freighter traffic to Dubai World Central, the emirate’s other main airport.

December’s freight volume decreased seven per cent to 202,836 tons.