Western Russia's Belgorod and Kursk regions came under attack from militia groups fighting on the side of Ukraine early Tuesday, with Russian regional authorities claiming that a "sabotage and reconnaissance group" failed to break through the border with Ukraine, Paralel.Az reports citing The Moscow Times.

Unverified videos shared on the Telegram messaging app had earlier shown what appeared to be armed vehicles entering villages in at least one of the border regions. In one video, gunfire can be heard.

The anti-Kremlin volunteer militia groups Freedom of Russia Legion and Russian Volunteer Corps, both of which fight on the side of Kyiv, said they were "on the attack" and "crossing the border" into Russia.

The Kursk region's governor confirmed that an armed group had launched an assault from Ukraine.

"A sabotage and reconnaissance group attempted to break through [the border], there was a firefight. But there was no breakthrough," Governor Roman Starovoit said in a video message on Telegram.

He said the attack had targeted the village of Tyotkino, which is located right on Russia's border with Ukraine.

Starovoit said one civilian was injured during the attack.

Authorities in the Belgorod region, while reporting a string of Ukrainian drone attacks across the region, had not confirmed whether an armed group had launched an incursion over the border.

Russia's Federal Security Service (FSB) denied reports that armed militia groups had managed to enter the Kursk and Belgorod regions, according to state-run media.

The FSB said it had "stopped several attempts to violate the state border" of Russia since Sunday, as quoted by the TASS news agency.

"Over 100 enemy personnel, six tanks, Caesar self-propelled guns, 20 units of armored combat vehicles, a strong point have been destroyed,” the law enforcement agency said without specifying whether those figures accounted for the reported incursions on Tuesday or for previous days as well.

A spokesman for Ukraine's military intelligence agency later said that the Russian volunteer groups were not acting under orders from Kyiv in launching their assaults.

"On the territory of the Russian Federation, they act absolutely autonomously, on their own, and pursue their social and political program tasks," GUR spokesman Andriy Yusov told Ukrainian media.