The imam of Mecca's Grand Mosque denounced those who "cause conflict among Muslims" in his final Friday sermon before the annual Hajj pilgrimage, as rifts widen among Gulf neighbours and wars continue across the Middle East.

Saudi Arabia, which hosts and supervises the Hajj, has with other Arab governments imposed sanctions on Qatar and cut all transport links with the country in recent months, accusing it of supporting Iran and backing terrorism - charges Doha denies.

Relations between Shia Muslim-led Iran and predominately Sunni Saudi Arabia are at their worst in years, with each accusing the other of subverting regional security and supporting opposite sides in conflicts in Syria, Iraq and Yemen.

"Anyone who causes conflict and discord among Muslims ignores the blessing of harmony, imitates those who lived in ignorance [before Islam], harms his people and cheats his nation," Sheikh Saleh Mohammed al-Taleb told the hundreds of thousands of pilgrims who have flocked to Mecca from around the world to perform the annual pilgrimage next week.

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Worshippers on Friday filled the mosque's haram sanctuary, the holiest place in Islam, and spilled into nearby streets, malls, hotel lobbies and garages, listening to the sermon through loudspeakers.

Taleb did not directly refer to the political and military divisions in the Arab world that have killed hundreds of thousands of people and displaced millions more in recent years.

Nearly 90,000 Iranians are expected to attend, after Tehran boycotted Mecca last year following a crush at the pilgrimage in 2015 in which hundreds of people died, many of them Iranians.

Qatar crisis

Saudi officials say over 400 Qatari pilgrims have also arrived through the land border in recent days, but Qatar has accused Saudi Arabia of deliberately making it hard for them.

Saudi Arabia says Qatar is seeking to politicise the ritual for diplomatic gains.

The dispute has defied mediation attempts by the United States and Kuwait.

The Qatari Ministry of Awqaf and Islamic Affairs, which regulates and organises the annual Hajj for Qatari citizens and residents, has said it did not receive responses from its Saudi counterpart on travel logistics or security guarantees.

Saad Sultan al-Abdullah, director of international cooperation at Qatar's National Human Rights Commission, expressed concern that Muslims were being prevented from performing their religious duty.

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"There should be no mixing between political disputes and Muslims' natural and human right to perform their religious duties," he said. "Politics and human rights must be separated."

Abdelmajid Mrari, head of the Middle East and North Africa division at the Brussels-based Alliance for Freedom and Dignity, criticised Saudi authorities for mishandling the situation.

"Mecca is not owned by any government. Mecca is for all Muslims," Mrari told Al Jazeera over the phone from France.

"The Saudi behaviour is a clear violation of Islamic values and norms, as well as all international human rights agreements and conventions."