SCOW, July 15 (Reuters) - Russia will increase its production of Sukhoi Superjet 100 aircraft and plans to deliver 30 of the planes to domestic airlines by the end of 2021, the head of the state-owned United Aircraft Corporation (UAC) said on Thursday.

The regional jet entered service in 2011 and was the first passenger jet built in Russia since the fall of the Soviet Union. The state has poured billions of dollars into its development. It is only used by Russian airlines.

"The Sukhoi Superjet is ... used intensively at this difficult pandemic time as air traffic has fallen," the UAC executive, Yury Slyusar, told President Vladimir Putin at a meeting on Thursday.

Thirty of the planes will be delivered to airlines this year, bringing the number of operational Superjets to more than 180, Slyusar said. Only 12 of them were delivered to airlines last year, its manufacturer, Irkut Corporation, has said.

Russia, like other countries, has restricted international air traffic due to the coronavirus since last year, but domestic flight routes that the Superjets flies are already recovering.

Superjets were initially exported to foreign airlines, but they later returned the aircraft, citing technical maintenance difficulties. The plane is currently operated only by Russian airlines, including state-owned Aeroflot and private airline Azimuth. (Reporting by Gleb Stolyarov; editing by Tom Balmforth and Sandra Maler)