KYIV - Armed fighters purporting to be Russian citizens who oppose the Kremlin said they carried out cross-border incursions into western Russia from Ukraine using tanks on March 12, but Moscow said it had repelled the attacks.

Ukraine said the groups were acting independently. But the border raids, carried out days before a presidential election in Russia and just over two years after Moscow's full-scale invasion of Ukraine, were widely seen as backed by Kyiv.

"This is only the first day (of the operation). But the elections, as we know, are only at the end of the week... All the most interesting things are yet to come," said Mr Alexei Baranovsky, a spokesperson for the Freedom of Russia Legion.

The group said it had taken full control of Tyotkino, a village on the edge of Russia's Kursk region bordering Ukraine, and aired aerial footage, apparently shot by a drone, showing several soldiers running across a field.

Mr Baranovsky, speaking to Reuters on a Zoom call from an undisclosed location, said the bulk of the forces used in the operation were in the Kursk region.

He said the attack could force Russia to pull in reserves to defend the area, relieving Russian offensive pressure on Ukrainian troops in eastern Ukraine.

"We are distracting the reserves, the attention of the Russian army. They are forced to transfer reserves... this is also our contribution to the defence of Ukraine," he said.

The group said it had destroyed a Russian armoured personnel carrier and that the border incursions had been undertaken alongside two other Ukraine-based groups - the Russian Volunteer Corps and the Siberian Battalion.

Russia's Tass news agency cited the local governor as saying one person had been wounded by Ukrainian shelling in Tyotkino.

The Russian defence ministry said it had beaten back the attackers and forced them to retreat.

It said Ukrainian "terrorist formations" backed by tanks and armoured combat vehicles tried to invade in three separate directions in Russia's Belgorod region, which borders the Kursk region and Ukraine, at about 3am Moscow time (8am Singapore time).

It said four more attacks by Ukrainian "sabotage and reconnaissance groups" were repulsed around five hours later in the Kursk region.

The Belgorod and Kursk regions were also attacked by Ukrainian drones in the afternoon and a drone crashed into the Belgorod city administration building, injuring two people, the regional governor said.

Looming election

Reuters could not independently verify the battlefield statements by either side.

A spokesperson for Ukraine's military intelligence agency said the groups were acting independently of Ukraine, but Kyiv has never made clear how such groups have received advanced weapons and armoured vehicles.

The Freedom of Russia legion and Russian Volunteer Corps have said they were behind other cross-border raids.

Russian officials cast the groups as puppets of Ukraine's military and the US Central Intelligence Agency.

Two of the units alluded to Russia's presidential election this weekend in social media posts.

The Siberian Battalion posted a video which it said was an address to the Russian people from its fighters in Russia. In the video, a masked man in military uniform urged Russians to fight rather than vote.

"Guys, don't vote with ballots, vote with calibers (of guns)," he said.

The Freedom of Russia Legion's post also appeared to refer to the election, in which Putin is certain to win a fifth term.

"The people will vote for whom they want, not for whom they have to. Russians will live freely," the legion said on Telegram. REUTERS