The southern Russian frontier region of Belgorod has been pummelled by dozens of Ukrainian strikes in the past 24 hours, the governor said Friday.

The Belgorod region, hit by strikes throughout the Kremlin's Ukraine offensive, was this week the scene of an unprecedented two-day incursion from Ukraine, with Russia using troops and artillery to put it down.

Five districts were repeatedly attacked by drones, mortars and artillery and the village of Kozinka had been struck more than 130 times, Belgorod governor Vyacheslav Gladkov said on social media.

The attacks on the border region came as Kyiv said it was preparing for a major counteroffensive against Moscow's forces.

Gladkov did not report casualties in the attacks.

He said the Graivoron district, where Russian troops fought off the incursion from Ukraine earlier this week, saw the worst attacks.

The border village of Kozinka had damaged pavements and roads, Gladkov said.

The village of Glotovo was hit by six shells, shattering windows of houses, Gladkov said. He added that "explosive devices" had been attached to a village shop and Soviet-era house of culture.

Local forces had shot down a drone and two missiles over the village, he said.

The Shebekinsky border district was shelled 35 times, Gladkov said. The village of Novaya Tavolzhanka was hit by drones, mortars and artillery, he said.

Areas around the city of Belgorod, which has a population of around 330,000, came under fire 14 times, he said.

Russia earlier this week vowed an "extremely harsh" response to attacks on its soil.