The International Atomic Energy Agency (IAEA) said late on Monday that its representatives inspected a damaged cooling tower at the Russia-controlled Zaporizhzhia Nuclear Plant but could not immediately determine the cause of a fire there at the weekend.

Moscow and Kyiv have accused each other of starting the fire at the vast dormant nuclear power plant in Ukraine, with Russia blaming a drone attack and Ukraine saying it was likely Russia's negligence or arson.

The IAEA team found no immediate sign of drone remains and assessed that it was unlikely that the primary source of the fire began at the base of the cooling tower, the IAEA said in a statement on its website.

"The team has not been able to draw definitive conclusions (on the cause of fire) on the basis of the findings and observations so far," the agency said.

Neither Moscow or Kyiv have reported signs of elevated radiation. 

The IAEA said damage was most likely concentrated on the interior of the tower at the water nozzle distribution level, at roughly 10 meters (33 ft) high.

"The team confirmed that there were no significant signs of disturbance of the debris, ash or soot located at the base of the cooling tower," the IAEA said. "The nuclear safety of the plant was not affected, as the cooling towers are not currently in operation."

Russia captured the plant in southern Ukraine in 2022.