DUBAI • Saudi Arabia's top religious authority said Iran's leaders were not Muslims, drawing a rebuke from Teheran in an unusually harsh exchange between the regional rivals over the running of the annual haj pilgrimage.

The war of words on the eve of the mass pilgrimage will deepen a long-running rift between the Sunni kingdom and the Shi'ite revolutionary power.

They back opposing sides in Syria's civil war and a list of other conflicts across the Middle East.

Iranian Supreme Leader Ayatollah Ali Khamenei, in a message published on Monday, criticised Saudi Arabia over how it runs the haj after a crush last year killed hundreds of pilgrims. He said the Saudi authorities had "murdered" some of them, describing Saudi rulers as godless and irreligious.

Responding to a question by Saudi newspaper Makkah, Saudi Arabia's Grand Mufti Abdulaziz Al-Sheikh said he was not surprised at Ayatollah Ali Khamenei's comments.

"We have to understand that they are not Muslims...

"Their main enemies are the followers of Sunnah (Sunnis)," Mr Al-Sheikh was quoted as saying.

He described Iranian leaders as sons of "magus", a reference to Zoroastrianism, the dominant belief in Persia, as Iran was known, until the Muslim Arab invasion of the region 13 centuries ago.

Mr Al-Sheikh's remarks drew an acerbic retort from Iran's Foreign Minister Mohammad Javad Zarif who said they were evidence of bigotry among Saudi leaders.

"Indeed; no resemblance between Islam of Iranians & most Muslims & bigoted extremism that Wahhabi top cleric & Saudi terror masters preach," Mr Zarif wrote on his Twitter account.

Tensions between the two countries have been rising since Riyadh cut ties with Teheran in January following the storming of its embassy in the Iranian capital, itself a response to the Saudi execution of dissident Shi'ite cleric Nimr Al-Nimr.

REUTERS