SINGAPORE - Singapore Airlines hopes to sign an agreement with Boeing during Prime Minister Lee Hsien Loong's visit to Washington next week to buy more aeroplanes.

PM Lee said this in an interview with American news broadcaster CNBC that was released on Friday (Oct 20), when asked if there were new deals Singapore hoped to do with the United States.

In February, SIA agreed to place firm orders with Boeing for 20 777-9s and 19 787-10 Dreamliners, for additional growth and fleet modernisation through the next decade.

Singapore Airlines spokesman Nicholas Ionides confirmed that the aircraft order announced as a letter of intent earlier this year is expected to be formally signed during PM Lee's visit to Washington.

"More details will be announced after the signing of the purchase agreement with Boeing," he said.

The letter of intent that SIA signed with the US airframe manufacturer also included six additional options for each aircraft type, which would enlarge the deal to as many as 51 planes.

The proposed order, which is valued at US$13.8 billion (S$19 billion), based on published list prices, includes flexibility for the SIA Group to substitute the 787-10 orders for other variants of the 787 family.

The 777-9s are due for delivery from the 2021-22 financial year and the 787-10s for delivery from the 2020-21 financial year.