Singapore Airlines (SIA) has signed a Letter of Intent to order 20 Boeing 787-9 Dreamliners, with purchase rights for another 20 aircraft of the same model, SIA said in a statement on June 14.

The value of the firm order for 20 Boeing 787-9s, the newest version on offer, is 4.52 billion U.S. dollars at the current manufacturer catalog price, according to the statement.

Having a range of 15,900 to 16,300 kilometers, the Boeing 787-9 aircraft has a passenger capacity of between 250 and 290 in its standard three-class configuration, as well as space for some 20 tons of cargo.

The composites and advanced technology used in the plane will also enhance the fuel efficiency, performance capabilities and passenger comfort.

"The decision to purchase the 787-9 is the culmination of an extensive evaluation of the performance characteristics and operating economics promised for the different versions of Boeing's new 787 aircraft," the statement said, adding that the purchase is for fleet renewal and to cater for growth.

Scheduled to be delivered from early 2011 to mid 2013, the Dreamliners are expected to be deployed on routes to North Asia, the Indian subcontinent and the Middle East.

SIA said that it will select the engines to power the aircraft at a later date.