Pro-Ukrainian militias staged a brazen cross-border attack on Russia on Tuesday, fighters and Russia's defence ministry said, hours after Kyiv launched one of its largest drone attacks since the start of the war.
Groups of pro-Kyiv volunteer fighters, made up of Russians who oppose the Kremlin, said that they had broken into the Kursk region, while Moscow said it had foiled multiple Ukrainian attempts to infiltrate the border.
"We crossed the border," the Freedom of Russia legion, a militia that claims to be made up of Russian citizens fighting on behalf of Ukraine, said it a post on Telegram.
"An armoured personnel carrier has been destroyed. We carry on working," it said, publishing a video from a drone that claimed to show the vehicle being blown up and fighters on the streets of the village of Tyotkino, on the border between Russia and Ukraine.
Moscow said it had fought off multiple attacks to penetrate into both the Belgorod and Kursk border regions.
"At about 3 am (0000 GMT), Ukrainian terrorist groups, after intensive shelling of civilian sites, tried to invade Russian territory in three directions," Russia's defence ministry said.
"All the Ukrainian attacks were repelled. The enemy was hit by aircraft, rockets and artillery," it added.
Another attack at 8:00 am (0500 GMT) at Tyotkino was foiled, it added.
Kursk Governor Roman Starovoyt said that a shoot-out in his region had taken place, but a full-scale incursion had been thwarted.
"A sabotage and reconnaissance group tried to break through, there was a shooting battle, but there was no breakthrough," Starovoyt said in a video message published on Telegram.
Russia's FSB said that since Sunday it had repelled a number of attempted cross-border attacks in the Belgorod and Kursk regions, in a statement cited by Russian state media.
Another pro-Kyiv paramilitary group, the Russian Volunteer Corps, also said it had attacked across the border and posted night-vision video showing its troops engaged in a firefight.
Ukraine-based militias -- made up of Russian citizens who oppose Moscow's invasion and have taken up arms on the side of Kyiv -- have claimed to be behind previous armed incursions into Russian territory.
In March last year, Russia launched a wave of retaliatory missile strikes on Ukraine after it said a sabotage group killed civilians in an attack on the Bryansk border region.
The Russian Volunteer Corps claimed responsibility for that attack.
In December, the Freedom of Russia Legion said it had launched a cross-border attack in the Belgorod region.
The apparent border incursion came hours after Kyiv launched one of its most significant drone attacks on Russia so far in the two-year conflict.
The attacks appeared to hit two energy sites, including one of the country's largest oil refineries some 800 kilometres (500 miles) from the border.
Ukraine has claimed responsibility for a wave of drone strikes and blasts at Russian energy sites in recent months, justifying the attacks as legitimate targeting of infrastructure sites used to fuel the invasion.
A major oil refinery in Kstovo, just outside the city of Nizhny Novgorod, was attacked by drones early on Tuesday morning, the regional governor said.
Russia's Lukoil energy giant said it had "temporarily suspended" work at its oil refinery in the town, citing an unspecified "incident".
On its website, Lukoil describes the facility as "one of the leading oil refineries in Russia" with an annual refining capacity of 17 million tonnes.
Videos on social media showed a large blaze raging in a facility purported to be the refinery, billowing black smoke into the sky.
There was no comment from Kyiv on the apparent attack.
Russia's defence ministry on Tuesday said that it had destroyed 25 drones overnight in seven different regions -- most of which were over the border regions of Belgorod and Kursk.
Earlier in Oryol, around 160 kilometres from the border with Ukraine, another drone crashed into a fuel depot and ignited a fire, according to the regional governor.
