Strikes across Ukraine, Russian-occupied territory and Russia killed at least 16 people, authorities said, as the 40th anniversary of the Chernobyl nuclear disaster prompted fresh warnings about the risks posed by attacks near the plant during Russia’s more than four-year invasion of its neighbour.

The death toll from Russian drone and missile strikes on the city of Dnipro rose to nine, regional head Oleksandr Hanzha said on Sunday.

One man was killed in a Ukrainian drone strike on the port city...