Russia's national guard said on Thursday it was fighting off attacks from pro-Ukrainian groups in the region of Kursk, the latest in a recent string of clashes at the border.
In the neighbouring Belgorod region of Russia, officials announced that two people had been killed and nine more wounded in fresh aerial attacks on the border region overnight and early on Thursday.
Three separate groups of Ukrainian militias, mainly comprised of anti-Kremlin Russians, this week claimed to have captured the village of Tyotkino in a joint operation.
"Rosgvardia units are involved in repulsing an attack by enemy diversion groups near the village of Tyotkino in the Kursk region," the national guard said on Thursday.
In a joint statement, three pro-Kyiv volunteer groups called on authorities to evacuate civilians from the regions of Belgorod and Kursk.
"Civilians should not suffer from the war and any casualties in the process of fighting will be on the conscience of Starovoit and Gladkov," they added, naming the governors of the regions.
Belgorod governor Vyacheslav Gladkov wrote on social media that one woman was killed in the most recent Ukrainian air attack on Thursday and several others were wounded, without specifying what weapons were deployed.
"As a result of an explosion, a car driven by a female civilian overturned into a ditch. The woman died on the spot from her injuries," Gladkov said, adding that three other people had been wounded by shrapnel.
Overnight, he had said earlier, another person was killed and six others were wounded in a drone barrage.
Russia's defence ministry earlier this week rejected assertions that the militia groups had taken control of any Russian territory and claimed to have thwarted an attempted incursion using air, rockets and artillery fire.
And on Thursday, it said had fended off an attack by Ukrainian forces to enter the Belgorod region via the village of Spodariushino, without saying when it took place.
Russian President Vladimir Putin has said the wave of attacks are part of efforts to disrupt forthcoming elections in Russian and occupied regions of Ukraine this weekend.