LVIV: The Ukrainian state nuclear company said on Thursday most of the Russian forces occupying the Chernobyl nuclear power station had withdrawn, leaving a "small number" on the territory of the defunct plant.
There was no immediate comment from the Russian authorities and Ukraine's energy ministry later said it was still gathering information on whether the Russian troops had indeed pulled out.
The International Atomic Energy Agency (IAEA) said late on Thursday it was preparing to send a mission to Chernobyl.
Though Russian soldiers seized control of Chernobyl soon after the Feb. 24 invasion, the plant's Ukrainian staff continued to oversee the safe storage of spent nuclear fuel and supervise the concrete-encased remains of the reactor that exploded in 1986, causing the world's worst nuclear accident.
State-owned Energoatom said these workers had flagged earlier on Thursday that Russian forces were planning to leave the territory.
"The information is confirmed that the occupiers, who seized the Chernobyl nuclear power plant and other facilities in the exclusion zone, have set off in two columns towards the Ukrainian border with the Republic of Belarus," it said in a statement.
It said a small number of Russian troops remained at Chernobyl, but did not specify how many. Russian forces have also retreated from the nearby town of Slavutych, where workers at Chernobyl live, it said.
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In a separate online post, Energoatom said the Russian side had formally agreed to hand back to Ukraine the responsibility for protecting Chernobyl. It shared the scan of a document setting out such an arrangement and signed by individuals it identified as a senior staff member at Chernobyl, the Russian military official tasked with guarding Chernobyl, and others.
Reuters could not immediately verify the authenticity of the document.
Ukrainian energy minister Herman Halushchenko later said the ministry was aware the Russians had signed such a document, but cautioned that the situation was still unclear.
"We are observing what is happening there. So far we do not have the information 100% that they have left the power station," he said on national television.
Ukraine has repeatedly expressed safety concerns about Chernobyl and demanded the withdrawal of Russian troops, whose presence prevented the rotation of the plant's personnel for a time.
Earlier this week, workers at the site told Reuters that Russian soldiers had driven without radiation protection through the Red Forest, the most radioactively contaminated part of the zone around Chernobyl, kicking up clouds of radioactive dust.
Asked to comment on the accounts from Chernobyl staff, Russia's defence ministry did not respond.
Energoatom said that as a result of their concerns about radiation, "almost a riot began to brew among the soldiers," suggesting this was the reason for their unexpected departure.
The IAEA said it had not been able to confirm the reports of Russian forces receiving high radiation doses.
Earlier on Thursday, the head of Energoatom urged the IAEA to help ensure Russian nuclear officials do not interfere in the operation of Chernobyl and the Zaporizhzhia nuclear power plant, Europe's largest, which is also occupied by Russian soldiers.