Russia's foreign ministry has accused Ukraine of carrying out "an act of nuclear terrorism" following an alleged drone attack on the Kursk nuclear power station overnight.
The Ukrainian defence ministry did not immediately respond to a request for comment on the latest allegation, the second that Moscow has made in two days.
Yesterday, Russian President Vladimir Putin accused Ukraine of trying to strike Russia's Kursk nuclear power plant and said Russia had informed the UN nuclear safety watchdog about the situation.
According to Russian news agency TASS, Russia's foreign ministry said the latest attack required a swift response from the UN nuclear watchdog, who is due to visit the site.
The nuclear plant is located in the Kursk region of western Russia, where fierce fighting has raged since Ukrainian forces launched a surprise incursion on 6 August.
Russian state news agency TASS quoted an unnamed source as saying the drone was shot down near a storage facility for spent nuclear fuel. Reuters could not independently confirm details of the alleged incident.
TASS quoted Russian Foreign Ministry spokeswoman Maria Zakharova as saying it was an "act of nuclear terrorism" that required an immediate response from the UN watchdog, the International Atomic Energy Agency (IAEA).
The head of the IAEA Rafael Grossi is due to visit the power station next week. He has appealed for maximum restraint to avoid a nuclear accident.
Rosenergoatom, a unit of state nuclear firm Rosatom, said this morning that a power unit at the station will be put on scheduled maintenance on Sunday.
Meanwhile, Russia earlier suspended a ferry service between southern Russia and Crimea after a Ukrainian attack yesterday hit a vessel loaded with rail cars carrying fuel, Russia's Transport Ministry said.
Ukraine's Navy said that it had destroyed a ferry at Port Kavkaz in Russia's Krasnodar region, one of Russia's largest outlets on the Black Sea, which it said had been used to deliver fuel and weapons to Crimea, which Russia seized and annexed from Ukraine in 2014.
The Russian Transport Ministry said in a statement that the ferry service to Crimea had been temporarily suspended while clear-up work took place.
It said an alternative overland route could be used to send cargo to Crimea in the meantime.
The RIA state news agency, citing emergency services, said a fire sparked by the Ukrainian attack had "practically" not affected the port's infrastructure, but that the ferry struck by Ukraine was half submerged.
Local authorities had said earlier it had sunk.
The ferry was carrying 30 rail cars loaded with fuel according to Fyodor Babenkov, district head of the town of Temryuk which includes the port.
Russia's Emergencies ministry said yesterday that 17 people had been rescued after the attack and that one person was not accounted for.
The port of Kavkaz is one of Russia's largest outlets on the Black Sea.
It handles ships both for exports and for fuel supplies to Crimea, seized by Russian forces in 2014.
Separately, Indian Prime Minister Narendra Modi has arrived in Kyiv to hold talks with Ukrainian President Volodymyr Zelensky, the first trip by an Indian prime minister to Ukraine since Kyiv gained independence from the Soviet Union in 1991.
"Reached Kyiv earlier this morning. The Indian community accorded a very warm welcome," Mr Modi wrote on X. The Ukrainian railways company showed footage of him stepping off a train carriage and being received by Ukrainian officials.
In the run-up to the trip he said he was looking forward to sharing "perspectives on peaceful resolution of the ongoing Ukraine conflict".
