Two villages in Russia's western Bryansk region have been shelled by Ukrainian forces, but no one was injured, regional governor Alexander Bogomaz said in a series of posts on the Telegram messaging app on Friday.

Reuters could not immediately verify the reported attacks on Lomakovka and Novaya Pogoshch villages located close to the border with Ukraine's Chernihiv and Sumy regions.

Russian officials have reported intensified attacks from northern Ukraine and said that on Thursday Ukrainian troops attempted to cross the border into the Belgorod region, the first such incursion.

Belgorod governor Vyacheslav Gladkov said on Friday at least one incident of shelling had been reported overnight in the Shebekino district, and over 2,500 people were being evacuated from the area.

Ukraine denies its military is involved in the incursions and says they are conducted by Russian volunteer fighters.

Ukrainian authorities on Friday lifted air raid alerts across most of the nation, and officials in the capital Kyiv said defences appeared to have shot down more than 30 missiles and drones fired by Russia.

Moscow has launched around 20 separate missile and drone strikes against Ukrainian cities since the start of May.

Russia denies targeting civilians or committing war crimes but its forces have devastated Ukrainian cities and repeatedly hit residential areas.

Russia invaded Ukraine in February 2022 in what President Vladimir Putin called a "special military operation" to "denazify" the country, protect Russian speakers and defend its borders from aggressive Western ambitions.

Kyiv and its Western allies accuse Putin of barbaric tactics and an imperialist-style land grab in Ukraine. The war has killed tens of thousands and sent millions fleeing abroad.