Russia's defence ministry on Friday blamed an attack at the site of the Zaporizhzhia nuclear power plant in Ukraine on Ukrainian saboteurs, calling it a "monstrous provocation".
Ukraine has said Russian forces attacked the plant in the early hours of Friday, setting an adjacent five-storey training facility on fire, in an incident that provoked international condemnation of Moscow, eight days into its invasion of Ukraine, reports Reuters.
Reuters could not independently verify either the Russian or the Ukrainian account of the incident.
A Russian defence ministry spokesman said the nuclear plant was operating normally and the area had been under Russian control since Feb 28.
"However, last night on the territory adjacent to the power plant, an attempt was made by the Kyiv nationalist regime to carry out a monstrous provocation," spokesman Igor Konashenkov said.
"On March 4 at about 2 am during a patrol of guarded territory adjacent to the Zaporozhye nuclear power plant, a mobile patrol of the National Guard came under attack from a Ukrainian sabotage group," he said.
"To provoke return fire on the building, heavy small arms fire was opened on Russian National Guard servicemen from the windows of several floors of a training complex located outside the power plant."
He said the Russian patrol returned fire to suppress the attack, and the "sabotage group" abandoned the training complex, setting fire to it as they left.
The account was diametrically opposed to Ukraine's version of events.
Earlier, a video from the plant verified by Reuters showed a building aflame, and a volley of incoming shells, before a large incandescent ball lit up the sky, exploding beside a car park and sending smoke billowing across the compound.