Nuclear watchdog slams lack of access to Europe's largest plant

However, his team is struggling to get access to Zaporizhzhya after it was occupied by Russian troops.

Grossi has returned from Ukraine, where a team of experts have checked radiation levels at the Chernobyl power plant, and re-established connection between the Vienna-based agency and the power plant.

There has been an increase in radiation at the site of the Chernobyl power plant in Ukraine which has been occupied by Russian troops for a month and cut off from the international nuclear watchdog.

But the increase is still "significantly below" the level authorised for workers in an environment, and the situation is stable.

"There was an increase in the levels, but the situation is not one that can be judged as posing great danger to the environment or people," Grossi said.

In February, Russian troops temporarily occupied the Chernobyl plant and Ukrainian officials claimed that soldiers had been exposed to high doses of radiation from digging into contaminated soil.

"This is not a place to have a picnic or excavate," Grossi insisted, even if his team's findings did not back up the claims of the Ukrainian officials.

However, Europe's largest nuclear power plant is still under Russian occupation, and the "Ukrainian regulator is not in control of the situation" at Zaporizhzhya, Grossi added.

IAEA experts want to check the safety of the equipment, and material there.

"[But] there are a number of activities that need to take place in terms of both inspections and safeguard activities that we will have to perform sooner rather than later," he said.

In early March, a Russian missile hit a building close to the reactor, raising concerns over nuclear safety both in Ukraine, and ultimately across the continent of Europe.

Grossi had a meeting with Ukrainian president Volodymyr Zelensky and in the coming days will meet with Russian officials to discuss access to the Zaporizhzhya site.

On Tuesday, Zelenskyy marked the 36th anniversary of the Chernobyl nuclear disaster by condemning Russia's "completely irresponsible actions" towards nuclear stations.

"We have to go there," Grossi said, adding that experts need to verify tens of thousands of nuclear materials, including plutonium, and enriched uranium.