Saudi Arabia's health ministry has ruled that only people who have been vaccinated against Covid-19 will be allowed to attend the Hajj this year, Saudi newspaper Okaz reported on Monday.

"The COVID-19 vaccine is mandatory for those willing to come to the Hajj and will be one of the main conditions (for receiving a permit to come)," the report said, citing a circular signed by the health minister.

Saudi Arabia stakes its reputation on its guardianship of Islam's holiest sites in Mecca and Medina and its peaceful organisation of the Hajj, which has been marred in the past by deadly stampedes, fires and riots.

In 2020, the kingdom dramatically reduced the number of pilgrims to around 1,000 to help prevent the spread of the coronavirus, after barring Muslims abroad from the rite for the first time in modern times.

Hajj, a once-in-a-lifetime duty for every able-bodied Muslim who can afford it, is a major source of income for the Saudi government.

Crowds of millions of pilgrims from around the world would likely be a hotbed for virus transmission. In the past some worshippers have returned to their countries with respiratory and other diseases.