Two Russian fighter jets and two military helicopters were shot down near the Ukrainian border on Saturday, in what would be a spectacular coup for Kiev if confirmed, according to the Russian news agency Kommersant.

According to Kommersant, a respected, independent business-focused daily, the Su-34 fighter-bomber, Su-35 fighter, and two Mi-8 helicopters were part of a raiding group and were “shot down almost simultaneously” in an ambush in the Bryansk region, bordering northeast Ukraine.

“According to preliminary data … the fighters were supposed to deliver a missile and bomb attack on targets in the Chernihiv region of Ukraine, and the helicopters were there to back them up – among other things to pick up the ‘Su’ crews if they were shot down.”

The Russian state news agency TASS said a Russian Su-34 warplane had crashed in that region but did not specify a cause.

TASS also cited an emergency services official as saying an engine fire in a helicopter had caused it to crash near Klintsy, which is about 40 km (25 miles) from the border.

It made no mention of the Su-35, or of a second helicopter.

However, a video posted on the Russian pro-war Telegram channel Voyenniy Osvedomitel, which has about half a million followers, showed a helicopter high in the sky suffering an explosion, being thrown off course and then plunging towards the ground in flames.

Comments accompanying the video, which Reuters could not immediately verify, said it showed a Mi-8 being shot down by a missile. Other images posted by the channel showed wreckage in an agricultural field.

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 Moscow Defence Ministry did not immediately respond to a request for comment.

Voyenniy Osvedomitel said it appeared that “most likely, the enemy staged an ambush with air defences previously transferred to a border zone close enough to hit our group”.

It said the downed helicopters appeared to be Mi-8MTPR-1 electronic warfare craft able to jam enemy radio and targeting signals.

Kommersant said all four crews had been killed.

There was no official response from Ukraine, which usually declines to comment on reports of attacks inside Russia.

However, in a tweet, Mykhailo Podolyak, a senior adviser to Ukrainian President Volodymyr Zelenskiy, called the incident “Justice … and instant karma”.