"In general, we are very positive about the fact that, despite all the difficulties and problems... the commission arrived and started to work," Kremlin spokesman Dmitry Peskov told reporters.

He added, however, that it was "too early" to evaluate the UN team's work.

"The main thing is that the mission is there," he said.

A team of inspectors led by International Atomic Energy Agency (IAEA) chief Rafael Grossi on Thursday visited Zaporizhzhia -- Europe's largest nuclear facility -- that has been held by Russian troops since early March.

Kyiv and Moscow have blamed each other for repeated shelling of the plant that has raised fears of a possible nuclear incident.

Several members of the IAEA team remained at the plant after Thursday's visit.