KIEV — The Russian-controlled Zaporizhzhia nuclear plant in Ukraine has lost its link to its last remaining main power line, the UN nuclear watchdog said.

The International Atomic Energy Agency (IAEA) added that the plant, Europe's largest, is now relying on a reserve line to supply power to Ukraine's grid.

Separately, Ukraine's state nuclear company said only one of the station's six reactors now remains in operation.

Both Ukraine and Russia accuse each other of repeatedly shelling the plant.

Inspectors from the IAEA arrived at the nuclear plant on Thursday amid security concerns.

After inspecting it, the agency's chief Rafael Grossi said the integrity of the plant had been "violated several times".

Located in the city of Enerhodar in southern Ukraine, the Zaporizhzhia nuclear plant is still being operated by Ukrainian staff.

They have said Russian troops are using it as a military base and that workers are in effect held at gunpoint.

The IAEA said in its statement that its presence at the plant was a "game-changer" as it had received fast and reliable information about the latest development.

"The agency's experts were told by senior Ukrainian staff that the [Zaporizhzhia nuclear power plant's] fourth operational 750 Kilovolt (kV) power line was down," it said.

"The three others were lost earlier during the conflict."

However, a 330/750 kV reserve line was delivering energy to the grid and could provide power to the plant if necessary, it added.

The IAEA noted that the main power line was also temporarily disconnected on Aug. 25.

Meanwhile, Russian-appointed local officials said the latest cut was caused by "technical problems" resulting from shelling.

Separately, Ukraine's state-run nuclear power operator Enerhoatom said that the plant's reactor No, 5 had to be switched off from the grid due to "non-stop shelling by occupying Russian forces".

Russia has not commented on the statement.

In yet another development, the Russian Defense Ministry said it had thwarted an attempt on Friday evening by Ukrainian armed forces to seize the plant. It provided no evidence to back up its claim, which has not been verified. — BBC