Ukraine has thwarted an attempt overnight by a Russian saboteur group to cross its northeastern border in the Sumy region, Serhiy Naev, commander of the joint forces of the Armed Forces of Ukraine, said on Thursday.

"The saboteurs tried to cross the state border of Ukraine and intended to move further towards one of the civilian critical infrastructure facilities," he wrote on the Telegram messaging app.

The eight-member group was repelled by Ukrainian fire, he said, adding that there were no losses among Ukrainian troops. (Reporting by Anna Pruchnicka; Editing by Edmund Klamann)