STORY: Klyntsy is about 25 miles (40 km) from the border in the Bryansk region, where Kommersant said the incident took place.
Kommersant said on its website that the Su-34 fighter-bomber, Su-35 fighter and two Mi-8 helicopters had made up a raiding party, and had been "shot down almost simultaneously" in an ambush in Bryansk, adjoining north Ukraine.
Kommersant provided no evidence for its report that four aircraft had been downed, but the same assertion was also made by several heavily followed pro-war military bloggers.
The Russian state news agency TASS said a Russian Su-34 warplane had crashed in that region but did not specify a cause. It also cited an emergency services official as saying an engine fire in a helicopter had caused it to crash near Klyntsy, but made no mention of any Su-35, or a second helicopter.
The Moscow Defence Ministry did not immediately respond to a request for comment.