Sukhoi is to sign a firm agreement covering 30 Superjet 100 aircraft with a southeast Asian carrier at the upcoming Farnborough Air Show.
The identity of the carrier has not been disclosed.
Indonesian operator Kartika Airlines concluded a tentative deal for 15 firm and 15 optioned aircraft in late 2008.
Sukhoi confirms that a "firm contract" with an airline from the region "is planned" during the show.
"The main objective of participating in the air show will be to promote the medium-haul Superjet 100 passenger aircraft," it adds.
Southeast Asia is one of the core markets into which the airframer hopes to sell the type.
Sukhoi has several tentative agreements outstanding for the Superjet, including one from Lao start-up carrier Phongsavanh Airlines.
Its official order book lists firm agreements for 101 of the twin-jet aircraft.