Plumes of black smoke were seen billowing in the distance off one of the towers at a Ukranian nuclear plant.
Russian forces started a fire on a nuclear power station in southern Ukraine to “blackmail” Kyiv as it pushes into Russian territory, Volodymyr Zelenskyy said.
A Ukrainian official said there was “unofficial” information that Russia on Sunday had set fire to a large number of car tyres on the cooling towers of the facility in Zaporizhzhia, which it occupied shortly after launching an invasion in February 2022.
Footage circulated on social media shows plumes of black smoke pouring off one of the towers.
While radiation is said to be at normal levels, it may have been a warning to Kyiv as it advances into Russian territory after launching a cross-border invasion on August 6.
Zelenskyy, the Ukrainian president, accused Moscow of attempted blackmail and said it “must be held accountable” for the provocation.
“Currently, radiation levels are within norm. However, as long as the Russian terrorists maintain control over the nuclear plant, the situation is not and cannot be normal,” he wrote on X, formerly Twitter.
“Since the first day of its seizure, Russia has been using the Zaporizhzhia NPP [nuclear power plant] only to blackmail Ukraine, all of Europe, and the world.
“We are waiting for the world to react, waiting for the IAEA [International Atomic Energy Agency] to react.
“Russia must be held accountable for this. Only Ukrainian control over the Zaporizhzhia NPP can guarantee a return to normalcy and complete safety.”
The blaze broke out at a cooling tower “after an attack by the Ukrainian armed forces”, Vladimir Rogov wrote on Telegram after Kyiv blamed Russia for the incident.
The IAEA said its experts “witnessed strong dark smoke coming from ZNPP’s northern area following multiple explosions heard in the evening”.
The Russian-occupied facility’s management claimed a drone attack had taken place on one of the cooling towers.
The ZNPP said in a statement that it had contained the fire and that there was no threat of it spreading further.
It comes as Kyiv attempts to push further into the Kursk region after launching a surprise offensive earlier this month – the first foreign invasion of Russian soil since World War II.
Russia’s defence ministry indicated that Ukraine had penetrated at least 32km into its territory, claiming to have “foiled attempts” by groups using armoured vehicles to break through defensive lines near the villages of Tolpino and Obshchy Kolodez.
According to images analysed by the BBC, Russia is building new defensive trench lines in the region, a short distance from one of its own nuclear power stations.
Heavy machinery can reportedly be seen next to a long line of piled earth south-east of the Kursk facility.