President Volodymyr Zelensky of Ukraine called the damage “significant” but said there were no signs of radiation leaks. A Kremlin spokesman denied that Russia had carried out the strike.

A drone armed with a warhead hit the outer shell of Ukraine’s Chernobyl nuclear plant, briefly starting a fire, in an attack Kyiv blamed on Russia.

A Russian drone caused significant damage to the radiation containment shelter at the Chornobyl nuclear power plant overnight, Ukrainian President Volodymyr Zelenskiy said on Friday.