STORY: Ukraine's Zaporizhzhia nuclear plant again lost connection to the last remaining main external power line, the U.N. nuclear watchdog International Atomic Energy Agency said on Saturday, while Moscow keeps its main gas pipeline to Germany shut, stepping up an energy war with the West.

Zaporizhzhia, Europe's largest nuclear power station, has been controlled by Russian troops since soon after their invasion of Ukraine in February. The IAEA also said only one of the station's six reactors remained in operation, but it continues to supply electricity to the grid through a reserve line.

It has become one of the focal points of the conflict, with each side blaming the other for shelling around the plant.

Transmission lines to the plant were cut last week and the facility was cut off from the national grid for the first time in its history, prompting power cuts in various regions of Ukraine. Emergency generators kicked in to keep the vital cooling process running.

Ukrainian President Volodymyr Zelenskiy blamed Russian shelling for the cutoff and said a radiation leak had narrowly been avoided, while Russia's defense ministry on Saturday blamed Ukraine for the shelling.

Reuters could not confirm any details of the Russian accusations.

Ukraine and the West have said Russia is using the site as a base for heavy weapons in a move to discourage Ukraine from firing on it, which Russia denies. Russia has so far resisted international calls to pull troops out of the plant and demilitarize the area.

Meanwhile, Russia kept one of its main gas supply routes to Europe shut on Saturday, stoking fears of winter fuel shortages.

Already struggling to tame soaring gas prices, European leaders had expected the Nord Stream 1 pipeline to resume flows after maintenance this week, but Russia abruptly canceled the restart, citing an oil leak.

Europe has accused Russia of weaponizing energy supplies in what Moscow has called an "economic war" with the West over the fallout from Russia's invasion of Ukraine. Moscow puts the blame on Western sanctions and technical issues for supply disruptions.