The International Atomic Energy Agency says it has been informed by Ukraine that the first staff rotation in three weeks at the Chornobyl Nuclear Power Plant has taken place.

A rotation of technical staff had been delayed multiple times since late February when Russian troops took control of the site, also known as the Chernobyl plant.

This led the IAEA to raise concerns about the plant's safety.

In a Sunday statement, IAEA Director General Rafael Mariano Grossi welcomed the development "as a much-needed positive step."

He said "it is clear that a lot of work remains to return the site to normality" and added that he will lead an IAEA mission to the plant as soon as possible.