Israel's massive strikes on Iran, which it calls an existential threat, have hit nuclear and military facilities, killed top commanders and dozens of civilians, and sought to destroy the country's defence capabilities.

Iran called the Israeli air assault "a declaration of war" and fired dozens of missiles at Israel later Friday and Saturday.

Oil prices soared more than 12 percent and stocks sank Friday after Israel launched strikes on Iranian nuclear and military sites and warned of more to come, stoking fears of a full-blown war.

Iran's Revolutionary Guards chief Hossein Salami, who was killed in an Israeli air strike on Tehran Friday, was a veteran officer close to supreme leader Ayatollah Ali Khamenei known for his tirades against Israel and its US ally.

Middle East leaders and their Western allies have been warning that ISIS could exploit the fall of the Assad regime to stage a comeback in Syria and neighbouring Iraq, where the extremist group once imposed a reign of terror over millions.

Iran's top diplomat and chief nuclear negotiator will meet the head of the International Atomic Energy Agency in Cairo on Monday, Egypt's foreign ministry said.

Iran seeks joint uranium enrichment with UAE and Saudi Arabia to ease US pressure and gain Gulf backing for its nuclear programme.

The US president indicated that he wouldn’t allow exceptions for power generation

Israeli Prime Minister Benjamin Netanyahu called Sunday for the complete dismantling of Iran's nuclear programme, insisting that any deal with Tehran must also address its ballistic missile capabilities.

Moscow and Tehran have pledged to oppose foreign pressure while enhancing cooperation

Both sides described the negotiations in Oman as “constructive” and have reportedly agreed to meet again for “real talks”

Tehran has reportedly deemed it unrealistic to reach a comprehensive accord within the two-month timeframe set by the US