Iran's supreme leader Ayatollah Ali Khamenei said "improper measures" and "mismanagement" by Saudi authorities caused Thursday's deadly stampede at the annual hajj pilgrimage, and he announced three days of national mourning.

"The government of Saudi Arabia must accept the huge responsibility for this catastrophe," state news agency IRNA quoted him as saying of the tragedy, which killed more than 700 pilgrims, including at least 90 Iranians.