Ukrainian President Volodymyr Zelenskyy says his country will keep working with the international community to step up pressure on Russia.

Zelenskyy said in a video message on Sunday that "all elements of the Russian system that are involved in the war, in providing terror and financing aggression must be isolated from the global system."

He also said his country will put into effect fresh sanctions on Russia's nuclear industry.

Zelenskyy's remarks come as Moscow is intensifying its attacks in and around eastern Ukraine. Russia is trying to seize control of Bakhmut, a Ukrainian stronghold in the eastern region of Donetsk.

The chief of a private Russian military company, Wagner Group, said on social media on Sunday that the mercenary force had taken a village near Bakhmut.