Russian officials on Thursday accused Ukraine of sending helicopters to bomb a town in the southern Bryansk region about 10 kilometers (six miles) from the border, after reporting seven injured in shelling.
"Using two military helicopters carrying heavy weaponry, Ukrainian armed forces illegally entered Russian air space," Russia's Investigative Committee — which probes major crimes — said in a statement.
"Flying low, acting deliberately, they carried out at least six air strikes on residential buildings in the settlement of Klimovo," investigators said.
As a result, they said, "at least six residental buildings were damaged... and seven people received injuries of varying severity including one small child born in 2020."
This appeared to be the first time that Moscow has officially accused Ukrainian armed forces of flying helicopters into Russia to carry out an attack.
Previously the governor of Belgorod region in southern Russia, Vyacheslav Gladkov, said two Ukrainian military helicopters had carried out a strike on a fuel depot on April 1, while this was not directly confirmed by Ukraine or Moscow.
Thursday's shelling was announced earlier by governor Alexander Bogomaz, who said on Telegram that "two residential buildings were damaged and some of the residents were injured."
A Russian Health Ministry official, Alexei Kuznetsov, told the RIA Novosti news agency that the seven injured were in hospital, adding that two were in serious condition and required surgery.
The governor of Russia's Belgorod region, Gladkov, later said on Telegram that the village of Spodaryushino close to the border "came under shelling from the Ukrainian side" and residents from this and a nearby village had been evacuated as a precaution.
Also on Thursday, Russia's security agency the FSB told TASS news agency that Ukraine fired at border checkpoint where over 30 Ukrainian refugees were crossing into Russia.
It added that there were no injuries.
AFP could not independently verify the claims.