By Robert Wall

LONDON--JSC Aeroflot, Russia's largest airline, on Thursday said it would buy 20 more Superjet regional aircraft, providing a boost to the Russian builder of the plane that has struggled to win orders.

Aeroflot said the deal, which has a list price value of more than $700 million, would bring its fleet of Superjet planes to 50 aircraft by 2017.

The airline is taking the planes built by JSC Sukhoi Civil Aircraft in an 87-seat configuration including 12 business class seats and the rest in economy, it said.

The planes will service domestic routes at Aeroflot subsidiary airlines, it said, adding that those local operations saw 23.6% annual traffic growth in November.

"The new aircraft are expected to make a significant contribution to the group's future growth," Aeroflot said.

Aeroflot is the largest buyer of the Superjet. Italy's Finmeccanica SpA is a partner in building the plane and France's Safran SA is involved in producing its engines.

Write to Robert Wall at robert.wall@wsj.com

Subscribe to WSJ: http://online.wsj.com?mod=djnwires