U.N. nuclear watchdog chief Rafael Grossi said he will lead a mission to Chernobyl "very, very soon", after Ukraine said Russian troops had left the radioactive waste facilities.

The International Atomic Energy Agency (IAEA) Director General called the news "a step in the right direction" and informed that "there is a lot of work to be done" in the former nuclear facility.

"What's important here is to work on the nuclear safety and the security of the plant. I have said from day one that there is a real risk and that my intention was not to engage in a process of negotiating drafts after drafts after drafts of a paper," he said, explaining that "it doesn't make any sense in these circumstances."

Instead of a joint agreement, he explained, IAEA has been able to agree separately with Russia and with Ukraine on what work the agency is going to do.

"We agreed to have a rapid assistance mechanism, which means that in case - and hopefully this won't be happening - there was a situation, an emergency, that may be taking place, we are setting up a mechanism whereby we could be sending a team to assess and to assist almost immediately," the IAEA chief said.

"What's happening there has never happened before," Grossi added. "So many things that may be this disconnected or out of service, because of a number of reasons, interruption of power or physical damage, have never happened before. And we can provide them with advice, compare... It's not that they need us to do their job. They do know how to do their job, but this doesn't mean that there is not a lot of international assistance and cooperation ongoing and this case, in particular."

Grossi was speaking to journalists in Vienna, Austria, at the end of a trip to Russia and Ukraine.

On Friday, Grossi met Rosatom Director General Alexey Likhachev and other senior Russian officials in Kaliningrad. This followed his detailed discussions earlier in the week with senior Ukrainian government officials at the South Ukraine Nuclear Power Plant (NPP) on the concrete steps that need to be taken to deliver urgent technical assistance for nuclear safety and security in Ukraine.

The IAEA has still not been able to confirm reports of Russian forces receiving high doses of radiation while being in the Chornobyl Exclusion Zone.

Out of the country’s 15 operational reactors at four sites, Ukraine said eight were operating, including two at the Russian-controlled Zaporizhzhya NPP, three at Rivne, one at Khmelnytskyy, and two at South Ukraine. The other reactors are shut down for regular maintenance (including Unit 2 at Rivne which shut down recently), it added.

In relation to safeguards, IAEA said that the situation remained unchanged from that reported previously. The agency was still not receiving remote data transmission from its monitoring systems installed at the Chornobyl NPP, but such data was being transferred to IAEA headquarters from the other NPPs in Ukraine.