Irkut will start working on a concept for the MS-21-400 aircraft after it completes the final design work for the smaller variants of the narrowbody.
The company displayed a model of the -400 at the MAKS air show in Moscow, with a larger wing, winglets and longer airframe distinguishing it from the -300 and -200 variants.
It is also likely to be able to carry 212-230 passengers, and have a longer range. This would make it more similar to the Airbus A321 and Boeing 737-900ER.
"The -400 will be very different, but we are still studying the concept and the market for the aircraft," said Irkut president Alexy Fedorov. "Our focus is now on the -200 and -300 as we have firm orders for those."