The head of the UN’s nuclear watchdog has urged parties in the Israel-Iran conflict to exercise maximum restraint and lamented the impact the fighting could have on diplomacy with Tehran.

Rafael Grossi, head of the Vienna-based International Atomic Energy Agency (IAEA), spoke on Monday at an extraordinary meeting of the agency’s Board of Governors, as the fighting between the two regional powers continued for a fourth day.

“Military escalation threatens lives, increases the chance of a radiological release with serious consequences for people and the environment and delays indispensable work towards a diplomatic solution for the long-term assurance that Iran does not acquire a nuclear weapon,” he said.

Grossi also provided an update on Iran’s Natanz nuclear enrichment complex, which sustained significant damage in Israeli strikes on Friday.

While the underground section of the facility was not directly targeted, the equipment housed there may have suffered damage due to a power outage, he said.

The radiation contamination inside the facility is hazardous but manageable with appropriate respiratory protection, Grossi said.

“The level of radioactivity outside the Natanz site has remained unchanged and at normal levels, indicating no external radiological impact to the population or the environment from this event,” he continued.

In addition to Natanz, four nuclear sites in Isfahan were damaged in the attacks, according to Grossi. However, he noted no reported damage at the Fordo uranium enrichment plant, the Bushehr nuclear power plant, or a reactor currently under construction.

IAEA inspectors remain in Iran and are prepared to resume their monitoring activities as soon as conditions allow, Grossi confirmed.

The most recent IAEA report highlighted a significant recent increase in Iran’s stockpile of uranium capable of being used in nuclear weapons. Tehran continues to deny any intention to develop nuclear arms.