MECCA (Reuters) - The imam of Mecca s Grand Mosque denounced those who  cause conflict among Muslims  in his last Friday sermon before the annual haj pilgrimage, as rifts widen among Gulf neighbors and wars rage across the Middle East. Saudi Arabia, which hosts and supervises the haj, 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 Islamist terrorism - charges Doha denies. Relations between Shi ite 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 haj next week.  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. 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 politicize the ritual for diplomatic gains. The dispute has defied mediation attempts by the United States and Kuwait. 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. An elderly Tunisian pilgrim named Bakari Abdel Jalil attended in a white shirt and cap while other worshippers donned customary white robes. He said he hoped regional tensions would not affect the haj. 