A Russian drone attack has hit the radiation shelter protecting Chernobyl’s damaged nuclear reactor, Ukrainian President Volodymyr Zelensky has said, writes BBC.

The overnight strike at the nuclear plant, which is the site of the world’s worst nuclear accident, caused a fire that has since been extinguished, he added. As of Friday morning, radiation levels inside and outside Chernobyl remain normal and stable according to the UN’s nuclear watchdog (the IAEA).

Russia has denied any claims it attacked Chernobyl, stating its military does not strike Ukrainian nuclear infrastructure and “any claims that this was the case do not correspond to reality”.

The International Atomic Energy Agency (IAEA), which monitors nuclear safety around the world, said fire safety personnel and vehicles responded within minutes to an overnight explosion. No casualties were reported, the agency added. The agency remains on “high alert” after the incident, with its director general Rafael Mariano Grossi saying there is “no room for complacency”.

Zelensky posted footage on X appearing to show damage to the giant shield, made of concrete and steel, which covers the remains of the reactor that lost its roof in the explosion [the shield is designed to prevent further radioactive material leaking out over the next century. It measures 275m wide and 108m tall and cost USD 1.6bn to construct].

Since 1990, Prof Jim Smith from the UK’s University of Portsmouth has studied the aftermath of the nuclear disaster and, while he admits the strike was a “horrendous attack on a very important structure” he is “not concerned” about the radiation risk. He told the BBC a thick concrete “sarcophagus” below the damaged outer shield covers radioactive particles in dust from the explosion. A drone strike would not be strong enough to damage this protective layer, Prof Smith said.

Zelensky claimed the attack shows Russian President is “definitely not preparing for negotiations”, after US President Donald Trump said Putin had agreed to begin talks to end the war in a surprise announcement this week. “Every night, Russia carries out such attacks on Ukraine"s infrastructure and cities”, Zelensky said. He called for “unified pressure” to hold Moscow accountable.