Moscow's defence ministry said it had rushed its own troops and aviation units to the southwestern Kursk region after a morning raid by Ukrainian "sabotage" units -- the latest such cross-border attack throughout the conflict.

"Today the enemy made another attempt to break through into the territory of the Kursk region," Russia's defence ministry said in a statement on Tuesday evening.

"The enemy was hit with artillery fire, strikes by army aviation units and attack drones," it added.

Moscow said earlier it had rushed reserve forces to the border zone to defend against a Ukrainian force it said consisted of around 300 troops, 11 tanks and more than 20 armoured combat vehicles.

The attack started at 08:00 Moscow time (0500 GMT), the defence ministry said. At 18:20 (1520), it said the Ukrainian forces had been pushed back to their own territory.

Moscow said it inflicted "significant losses" on the "sabotage group" using drones, air strikes and artillery, repelling their attempts to "gain a foothold" inside Russian territory.

It published videos purporting to show Ukrainian tanks being hit from the air.

Footage on social media had earlier claimed to show Russian warplanes flying at low-altitude over the Kursk region as they battled to put down the attack.

The Russian governor of the region said three people had been killed throughout the day -- a woman in the attempted border incursion and two people whose vehicles were hit in separate drone attacks.

Several others were injured.

The Kursk region sits just across from Ukraine's northeastern Sumy region.

Ukraine did not comment on the reports but the head of the Sumy region military administration, Oleksiy Drozdenko, told residents to pay attention to air raid alerts.

Ukrainian forces said there was "cynical shelling" of border settlements in the Sumy and neighbouring Chernigiv regions.

- Village seized -

Combatants from Ukraine have made several brief incursions into Russia since the beginning of the conflict, including by units of Russians fighting in support of Kyiv -- the Russian Volunteer Corps and the Freedom of Russia Legion.

The latest attack comes almost three months after Russian President Vladimir Putin launched a major new offensive into northeastern Ukraine, a move he said was to create a security buffer to protect Russian border regions from shelling and aerial attacks.

That offensive was focused on Ukraine's Kharkiv region, to the southeast of the Sumy region, from where Tuesday's cross-border raid was mounted.

Russian authorities also said Tuesday that Ukrainian "saboteurs" had attempted a landing by sea on the Russian-held Tendra Spit in southern Ukraine.

"According to preliminary information, 12 high-speed craft were used -- eight of them with the saboteurs and four with fire support," Moscow-appointed governor Vladimir Saldo said on social media.

"Russian marines opened fire as the boats were approaching the Tendra Spit. Three boats were destroyed with their crews and sank. The others turned back," Saldo said.

Meanwhile, Russia's defence ministry said its forces had captured another village in eastern Ukraine, the latest in a series of gradual advances in recent weeks.

Russian units "liberated the settlement of Timofeevka," it said on social media, using the Russian name for the village, which is known as Timofiyivka in Ukrainian.

Earlier in the day, the head of Russia's General Staff, Valery Gerasimov, had visited troop positions in occupied parts of Ukraine's eastern Donetsk region, the defence ministry said.

The general "heard reports from the commanders of units ... summed up his conclusions and set tasks for future actions", the ministry said, posting video of Gerasimov meeting soldiers in underground locations.