Singapore budget carrier Tiger Airways said on Tuesday it had exercised an option to buy 20 Airbus A320 aircraft worth 1.3 billion US dollars.
European manufacturer Airbus had said in October that Tiger signed a contract for 30 medium-range, single-aisle A320s, with 20 more on option.
The 20 extra aircraft are for delivery by 2016, Tiger Airways chief executive Tony Davis told reporters.
The budget carrier has a fleet of nine A320s now and will have 70 by 2016 as it continues to expand its operations in the Asia-Pacific region.
The airline is 49 per cent owned by national carrier Singapore Airlines.
Southeast Asia's low-cost sector has boomed since the birth of Malaysia-based AirAsia almost six years ago spawned a host of imitators.