The short of it
The Red Cross has called for all fighting to stop around the Zaporizhzhia nuclear power plant in southern Ukraine and warned of a potential humanitarian disaster.
The plant has been under Russian control since March, and has been coming under fire in recent weeks sparking fears of a major disaster.
A team of UN experts arrived at Zaporizhzhia on Thursday to assess the risk of a radiation leak.
The long of it
The Red Cross has warned there is "very little" anyone could do to mitigate the "dire consequences" in the event of a nuclear leak at Europe's largest nuclear power plant.
The Zaporizhzhia nuclear power plant in southern Ukraine has been under Russia's control since early March, and recent imagery has shown they have an enhanced presence around the site.
It has been shelled in recent weeks, sparking fears of an accident just 500km from the site of the world's worst nuclear accident, the 1986 Chernobyl disaster.
Both the Ukrainians and the Russians have blamed each other for the shelling.
The last two working reactors at the Zaporizhzhia plant were disconnected from the Ukrainian grid on Thursday after nearby fires damaged overhead power lines, Ukraine's state nuclear company Energoatom said.
The head of the International Committee of the Red Cross called on Thursday for all fighting near the plant to stop, warning that little could be done to respond in the event of a major accident there.
"In the event of a nuclear leak, it will be difficult if not impossible to provide humanitarian assistance ... and this is why fighting should stop," Robert Mardini told a news conference during a visit to Ukraine.
"The scenario could be a massive incident, and ... there is very little anyone can do to mitigate the dire consequences of this."
A team of UN experts arrived at Zaporizhzhia on Thursday to assess the risk of a radiation disaster after being delayed several hours by shelling near the site.
Russia and Ukraine earlier accused each other of trying to sabotage the mission of the International Atomic Energy Agency (IAEA) to the plant in southern central Ukraine, which is controlled by Russian forces but operated by Ukrainian staff.
Ukraine's state nuclear company Energoatom said Russian shelling had forced the shutdown of one of only two operating reactors at the site, while Moscow said it had thwarted a Ukrainian attempt to seize the plant.
It said the other was continuing to provide power for the plant's own needs.
Russia's defence ministry said it was using helicopters to destroy a Ukrainian "sabotage group" that it said had landed near the plant, Interfax news agency reported.
It was claimed earlier this week that staff at the Zaporizhzhia plant have been tortured by occupying Russians to force them to operate the plant since it was captured.
Mardini welcomed the planned visit by the United Nations' nuclear watchdog to inspect the damage, warning an accident could have catastrophic and long-lasting consequences for millions of people and the environment.
"It is therefore time to stop playing with fire and instead take concrete measures to protect this facility, and others like it, from military operations," he said. "The slightest miscalculation could trigger devastation that we will regret for decades."
Mardini told Reuters that the Red Cross was not stockpiling or distributing iodine tablets to people near the plant to avoid sowing panic.
"We don't want to give a signal that this is inevitable," he said. "This is totally self-inflicted risk that should be totally stopped."