TEHRAN: Iranian Foreign Minister Mohammad Javad Zarif accused Saudi authorities of “bigoted extremism” late Tuesday in an increasingly bitter war of words over Iran's exclusion from this year's Haj.

Javad Zarif was responding to a claim by Saudi Arabia's most senior cleric, Grand Mufti Abdulaziz al-Sheikh, that Iranians were "not Muslims".

"Indeed, no resemblance between Islam of Iranians and most Muslims, and [the] bigoted extremism that Wahhabi top cleric and Saudi terror masters preach," Zarif tweeted.

Iran's supreme leader Ayatollah Ali Khamenei was due to meet later on Wednesday with the families of some of the more than 400 Iranian victims of a stampede that killed nearly 2,300 pilgrims at last year's Haj.

He published a scathing open letter on Monday, accusing the Saudis of failing to protect pilgrims.

"The hesitation and failure to rescue the half-dead and injured people... is also obvious and incontrovertible. They murdered them," he wrote.

For the first time in almost three decades, Iranians have been blocked from the annual pilgrimage to Islam's holiest places in Saudi Arabia after the regional rivals failed to agree on safety and logistical issues.

That has sparked acrimonious exchanges ahead of the start of the Haj on Saturday.

Khamenei described the Saudi royal family as "small and puny Satans who tremble for fear of jeopardising the interests of the Great Satan (the United States)”, and called on the Muslim world to end its management of the Haj.

The grand mufti responded on Tuesday, telling the Makkah daily: "We must understand these are not Muslims, they are children of Magi and their hostility towards Muslims is an old one."

"Magi" was a reference to the Zoroastrian religion that was prevalent in Iran before Islam, and is sometimes used as an insult against Iranians.

Iran and Saudi Arabia often vie for regional dominance, backing rival sides in conflicts from Syria to Yemen.