The head of the global nuclear watchdog says there has been no further damage to Iran's Natanz uranium enrichment plant since Israel struck the country's nuclear sites on Friday.

Rafael Grossi told the International Atomic Energy Agency's (IAEA) board of governors that an above-ground enrichment facility at Natanz was destroyed, but that there were no signs of a physical attack at the underground facility there.

Four buildings were also damaged at the Isfahan site, he said, including a uranium conversion plant, and no damage was visible at the underground Fordo enrichment plant.

Israel said it attacked the sites and killed nine nuclear scientists to stop Iran developing nuclear weapons.

It alleged that Iran had in recent months "taken steps to weaponize" its stockpile of enriched uranium, which can be used to make fuel for power plants but also nuclear bombs.