Russia and Ukraine said they repelled air attacks in border areas on Tuesday and Kyiv accused Moscow of pounding one northeastern region with 200 bombs in the past month.
Moscow said anti-aircraft units had downed missiles in two areas amid allegations of Ukrainian incursions in recent weeks in three Russian border regions - Belgorod, Kursk and Voronezh.
Intense Russian bombing of Ukraine's northeastern border region of Sumy meanwhile has prompted Kyiv to order mass evacuations.
Russia's Defence Ministry, posting on Telegram, said air defence units had intercepted 10 projectiles fired by Ukrainian multiple rocket launchers and one Tochka-U missile over Belgorod region at about 10 p.m. (1900 GMT)
Within half an hour, the ministry said it had intercepted two more missiles, including a U.S.-made Patriot, over neighbouring Kursk region.
No casualties were reported in either incident.
Ukrainian President Volodymyr Zelenskiy, in his nightly video address, decried "constant terrorist attacks and strikes" in Sumy region.
"Since the beginning of the month, Russian aviation has already dropped almost 200 guided bombs on the communities of Sumy region," he said. "Villages, cities, civilian infrastructure."
Authorities in Sumy said there had been 30 instances of shelling during the day. One person had been killed in the border community of Velyka Pysarivka, focal point of an evacuation which got under way last week.
Russia denies targeting civilians in its war on Ukraine launched more than two years ago, and Reuters was unable to independently verify the battlefield reports.
Over the border, Belgorod regional Governor Vyacheslav Gladkov said heavy shelling in the border community of Kozinka had damaged several dwellings.
