Saudi Arabia on Sunday denounced as "unacceptable" Iranian demands over its pilgrims joining the annual Islamic hajj this year, after Tehran accused Riyadh of raising obstacles.

"Iran has demanded the right to organise... demonstrations and to have privileges... that would cause chaos during the hajj. This is unacceptable," Foreign Minister Adel al-Jubeir said in a joint press briefing with his British counterpart Philip Hammond.

Tehran said earlier on Sunday that Iranians will miss the pilgrimage this year to Islam's holiest sites in Saudi Arabia, and accused Riyadh of "blocking the path to Allah".