Ukraine's Chernobyl nuclear power plant, the site of the world's worst nuclear disaster in 1986, has once again lost its electricity supply, energy operator Ukrenergo said Monday.

"The line that supplies the Chernobyl Nuclear Power Plant and the town of Slavutych was damaged by the occupying forces," Ukrenergo said on Facebook, referring to Russian forces that invaded Ukraine on February 24 and seized the plant in the first days of the assault.

The retired nuclear plant — enclosed in a giant steel and concrete sarcophagus — lost power early last week but supply was restored Sunday.

The plant has emergency diesel generators which can temporarily provide the electricity needed to power security systems including the cooling systems for a spent nuclear fuel storage facility, Ukraine's nuclear power inspection body SNRIU said last week.

Ukrenergo said the line was damaged again "before the power supply was fully restored" and that one of its repair crews will be going into "occupied territory" again for more repairs.

The operator added that Chernobyl "cannot be left without a reliable energy supply" and the residents of the nearby town of Slavutych "depend" on it for electricity.

An explosion at the Chernobyl nuclear power plant in 1986 killed hundreds and spread a radioactive cloud across Europe.

Russian forces also shelled and captured the Zaporizhzhia plant, Europe's biggest atomic power plant, on March 4, causing a fire that raised alarm in Europe over a possible nuclear catastrophe.

Power restored to Ukraine's Chernobyl plant, seized by Russian forces: Kyiv
Kyiv (AFP) March 13, 2022 – Electricity supply has been restored at Ukraine's retired Chernobyl nuclear power plant that was seized by Russian forces in the first days of the invasion, energy officials in Kyiv said Sunday.

"Today, thanks to the incredible efforts of (Ukrainian energy) specialists, our nuclear power engineers and electricians managed to return the power supply to the Chernobyl nuclear power plant, which was seized by the Russian occupiers," Ukraine's Energy Minister German Galushchenko said in a statement.

"Our Ukrainian energy engineers, by risking their own health and lives, were able to avert the risk of a possible nuclear catastrophe that threatened the whole of Europe," he added.

Power had been cut to the site of the world's worst nuclear disaster, though the UN's atomic watchdog said there was "no critical impact to safety".

An explosion at the Chernobyl nuclear power plant in 1986 killed hundreds and spread a radioactive cloud west across Europe.

Ukraine said on Wednesday power had been cut to the plant, but the UN's atomic watchdog said there was "no critical impact on safety".

Russian forces also shelled and captured the Zaporizhzhia plant, Europea's biggest atomic power plant, on March 4, causing a fire that raised alarm in Europe over a possible nuclear catastrophe.

Russian engineers arrived at Zaporizhzhia earlier this week to check radiation levels.

In his statement, Galushchenko also reiterated calls on the international community to help secure Ukraine's nuclear facilities and establish a 30-kilometre (18 miles) demilitarised protective zone around them.

"It is now extremely important to force the enemy to leave our our nuclear power plants," he said.