A Russian drone has hit the protective shelter over Chernobyl's damaged nuclear reactor, Ukrainian President Volodymyr Zelensky has said. The overnight strike at the site of the world's worst nuclear accident caused a fire that has since been extinguished, he added.

Ukraine said a Russian drone crashed into the containment structure, starting a fire, but so far radiation levels have stayed constant.

A drone armed with a warhead hit the protective outer shell of Ukraine's Chernobyl nuclear plant early Friday, punching a hole in the structure and briefly starting a fire, in an attack Kyiv blamed on Russia.