Iran's Revolutionary Guard Corps (IRGC) announced the beginning of what it said was the "most devastating offensive operation in the history of the Islamic Republic of Iran,” after the killings of Ayatollah Ali Khamenei and other senior officials were confirmed.

Axar.az reports, citing The National, that it said it had launched "extensive missile and drone" attacks on Israel and 27 US bases in the region.

The strikes killed the country's Supreme Leader Ayatollah Ali Khamenei on Saturday as well as other top officials, including the IRGC chief.

It said 27 American bases and the Tel Nof Airbase, the Israeli army's headquarters in Tel Aviv, as well as a large defence industrial complex were attacked.

Khamenei was killed on Saturday morning in a joint US-Israeli wave of strikes targeting Tehran and other Iranian cities, state media announced. It added that his daughter, son-in-law and grandson were also killed.

The government has declared 40 days of mourning.