Maj Gen Apti Alaudinov, commander of Chechnya's Akhmat special forces unit, said that 12,000 Ukrainian troops have entered Kursk Province, Al Jazeera Arabic reported.

Alaudinov conceded that Ukrainian troops have managed to take a certain number of settlements in Kursk, but added that Russian forces have almost "completely blocked" their further advance.

"Among them there were many foreigners, most of whom have been destroyed," Alaudinov said.

"Isolated" Ukrainian sabotage and reconnaissance groups are meanwhile being monitored by the Russian side, he said, according to Washington Post on Wednesday.

Alaudinov was even more defiant in comments aired on state Rossiya 1's 60 Minutes talk show. "We've already sunk our teeth in, and it's unlikely that we'll let the enemy go until we completely rip out its Adam's apple," he said.

Ukraine’s military mounted its largest drone attack on Russian airfields since the 2022, when Russian attack started, targeting four key sites deep inside Russian territory with dozens of drones overnight, as its forces continued their advance in the Kursk region of southern Russia.

Also on Wednesday, explosions were heard in the city of Odesa in southern Ukraine.