Qatar has signed a contract with US engineering giant Bechtel to build a new airport for its capital Doha.
Bechtel has won substantial contacts for Iraq reconstruction
The scheme is expected to cost a total of about $5bn. Passenger handling capacity will be boosted to 12m when the first phase is completed by 2009.
Last year, Qatar Airways signed a deal to buy 18 Airbuses with options on 14 more at a cost of £3bn.
The Gulf state plans to boost tourism and hopes to draw duty-free shoppers on routes linking Europe with Asia.
To occupy 2,200 ha (8.5 sq miles) east of current airport
Involves substantial reclamation of land from sea
Will have two parallel runways and more than two dozen gates
Includes HQ building for Qatar Airways
"The airport will be one of the biggest in the world, with an [annual] capacity of 50 million passengers in Qatar" when it is finished in about 2015, Civil Aviation Authority Chairman Abdul Aziz Mohamed al-Noaimi was quoted as saying.
Work on the three-phase project is expected to begin this year.
The privately owned San-Francisco-based Bechtel has won substantial contracts in Iraq. This month it was awarded a $1.8bn follow-on contract with the US Agency for International Development.