Ukrainian President Volodymyr Zelensky has described Russian forces’ actions at the Zaporizhzhia nuclear power plant as “nuclear blackmail” that may embolden malign actors worldwide.

He renewed his call for fresh sanctions against Moscow and its nuclear industry in response to the situation.

Russian and Ukrainian officials traded more accusations on Monday about renewed shelling of the plant, with each side alleging that the other was responsible for the attacks that have raised fears of a catastrophe.

The press office of the Kremlin-backed administration in Enerhodar, the Russian-controlled city where the plant is located, told the Interfax agency that Ukrainian forces were carrying out “massive shelling” of the facility, as well as Enerhodar’s residential and industrial areas.

According to the statement, the shelling came from nearby Nikopol, a Ukrainian-held city which faces the plant across the Dnieper River.

The mayor of Nikopol later said that Russians were shelling Enerhodar themselves.

Mayor Yevhen Yevtushenko and other municipal authorities in Nikopol have repeatedly accused Russian troops stationed at the plant of shelling the city, knowing that Ukrainian forces there were unlikely to fire back.

As Russian forces kept up their artillery barrages around Ukraine, at least three Ukrainian civilians were killed and 20 others wounded, Ukrainian officials said.

The deaths and injuries were blamed on Russian shelling that hit towns and villages in the Donetsk region, regional officials said.

In the country’s second-largest city of Kharkiv, seven civilians were wounded by Russian shelling that hit residential buildings and an area near a bus stop. Kharkiv Governor Oleh Synyehubov said the wounded included an 80-year-old woman.

Russian Defence Ministry spokesman Igor Konashenkov said on Monday that Russian warplanes have struck Ukrainian army positions in the southern Kherson region and in the Donetsk region.

He added that the Russian air force also hit a facility in the Kharkiv region, killing at least 100 and wounding 50 “mercenaries” from Poland and Germany. His claims could not be independently verified.

Speaking at the opening of an arms show outside Moscow, Russian President Vladimir Putin hailed the military, which he said was “liberating the Donbas step by step”.

He also vowed to expand arms sales to Russian allies, whom he praised for continuing to offer firm support to Moscow in the face of Western pressure.

For its part, the Ukrainian military claimed to have destroyed more than 10 Russian warehouses with ammunition and military equipment in the past week.