Zaporizhzhia -- Europe's largest nuclear energy facility -- has been at the centre of tensions in recent weeks after Moscow and Kyiv accused each other of strikes on and near the plant, raising fears of an atomic disaster.

Ihor Murashov was detained by a "Russian patrol" on Friday at around 4:00 pm local time (1300 GMT) on his way from the plant to the city of Energodar, the head of Ukraine's nuclear agency Energoatom, Petro Kotin, said in a statement.

He said Murashov's vehicle was stopped, he was taken out of the car and "with his eyes blindfolded, he was driven in an unknown direction".

Ukraine's foreign ministry said in a statement it "condemns in the strongest terms the illegal detention".

"The crime is yet another act of state terrorism by Russia and it represents a grave violation of international law. Russia must immediately release" him, it added.

Murashov "bears the main and exclusive responsibility for the nuclear and radiation safety" of the Zaporizhzhia plant, according to Kotin.

The nuclear plant is located in Russian-held territory of Ukraine's Zaporizhzhia region, which Russia on Friday annexed together with three other territories in Ukraine: Donetsk, Lugansk and Kherson.

Shelling around the plant has spurred calls from Kyiv and its Western allies to de-militarise areas around nuclear facilities in Ukraine.

A monitoring team from the UN visited Zaporizhzhia in early September.