“Our air defence fighters repelled the attack of the Ukrainian armed forces last night,” Kursk regional governor Alexei Smirnov wrote on his Telegram channel.

He did not provide further detail. The Russian defence ministry said in its morning update that a total of 23 Ukrainian drones were destroyed over the Russian territory. The ministry did not mention missiles in its statement.

A pro-Russian military analyst Roman Alyokhin, who serves as an adviser to the governor, said on Telegram that “Kursk was subjected to a massive attack by foreign-made missiles” overnight.

“It was very loud and there were a lot of them (missiles),” Alyokhin said.

Reuters could not independently verify the reports. It was not clear what weapons Ukraine used. There was no immediate comment from Ukraine.

Ukraine launched a surprise incursion into the Kursk region in August, but has since lost more than 40% of the territory it had captured as Russian forces have mounted waves of counter-assaults, a senior Ukrainian military source told Reuters.

After US president Joe Biden allowed Kyiv to fire US-supplied missiles at targets deep inside Russia, Ukraine last week fired ATACMS and Storm Shadow cruise missiles at Russian targets.

Moscow responded with a strike on Ukraine using a newly developed hypersonic ballistic missile.