The 777 is an intermediate twin-aisle aircraft, powered by Rolls-Royce Trent 892 engines. The 10 aircraft will be delivered between 2001 and 2004.

The options are part of an agreement the airline made in 1995 for 77 aircraft, comprising 34 on firm order and 43 on option. Rolls-Royce PLC said that it will get about $260 million from Singapore Airlines' order for the aircraft engines.

Singapore Airlines, which operates 89 aircraft, looks to expand this to 120 by 2005. It added that it expects to finance the purchase largely from its cash flow.

The airline said the acquisition of the Boeing 777-200s will allow it to phase out its A340-300 fleet of Airbus jets, which is currently deployed primarily on the thinner routes to Europe and North America. The carrier currently operates 89 aircraft, including seven freighters.

As of Thursday, European consortium Airbus Industrieappeared to be ahead of rival Boeing in the race to sign up new customers at the nine-day Paris Air Show. Airbus said it had booked 93 firm orders and 53 commitments for aircraft, worth a total of $6.9 billion since the show began Saturday.Boeing said it had booked firm orders worth more than $3 billion for 62 jetliners.

Of the $1.38 trillion that Boeing predicts that airlines will invest in new commercial airplanes during the next 20 years, the largest amount -- more than $570 billion -- will be dedicated to intermediate, twin-aisle airplanes, such as the 767 and 777. Single-aisle airplanes are a close second. The 747-and-larger airplanes will account for the smallest dollar investments, according to the 1999 Boeing Current Market Outlook, released at the Paris Air Show.