Saudi Arabia's top cleric has declared that Iran's leaders are not Muslims and regard Sunni Muslims as their enemy.

Grand Mufti Sheikh Abdul-Aziz ibn Abdullah Al ash-Sheikh was responding to Iran's supreme leader, who denounced Saudi Arabia's handling of the annual Hajj pilgrimage to Mecca.

The Grand Mufti said the claims of the Iranian Ayatollah were "not surprising" and accused Iran's leaders of being Zoroastrians, an ancient pre-Islamic Iranian religion.

Saudi Arabia's population is nearly 90 per cent Sunni and has long been at odds with the 95 per cent Shia Iran - two denominations that have been in conflict since the 7th century.

In remarks published on Wednesday, Sheikh Abdul-Aziz Al ash-Sheikh said: "We must understand these are not Muslims.

"They are the son of the Magi and their hostility towards Muslims is an old one, especially with the People of the Tradition [Sunnis]."

Iran's Ayatollah Ali Khamenei accused the Saudis on Monday of "murdering" pilgrims caught up in the stampede during last year's Hajj.

At least 2,426 people, including 464 Iranians, were killed in the stampede. According to Saudi authorities, only 769 were killed.

Without providing evidence, the Ayatollah said: "The heartless and murderous Saudis locked up the injured with the dead in containers.

"Instead of providing medical treatment and helping them or at least quenching their thirst. They murdered them."

(Independent)