World Bulletin/News Desk

A gathering of millions of Shi'ite Muslims at shrines and mosques across Iraq for the Ashura religious commemoration passed without any major attacks on Tuesday, under tight security imposed for fear of ISIL bombers.

Crowds of hundreds of thousands of people in the holy city of Kerbala had largely dispersed in safety after nightfall, following a day of worship and prayer to mark the 7th century battle that divided the Muslim world into Sunnis and Shi'ites.

But seven pilgrims returning home from Kerbala were killed in separate roadside bomb attacks in the town of Latifiya, 40 km (25 miles) south of Baghdad, police and medical sources said.

Dozens of pilgrims were killed in Baghdad alone in the run-up to this year's event, despite an increase in security since suspected suicide bombers and mortar attacks killed 171 people during Ashoura in Kerbala and Baghdad in 2004.

But no mass killings were reported in Iraq as Shi'ites across the Muslim world commemorated the slaying of Prophet Mohammad's grandson Hussein at the battle of Kerbala in AD 680.

Gunmen shot dead at least eight people in Saudi Arabia's Eastern Province, state news agency SPA reported, in what local residents said was an attack on Shi'ite Muslim worshippers on Monday night, testing already strained relations between Sunnis and Shi'ites across the Middle East.

In Kerbala, huge masses of pilgrims gathered outside the Shrine of Imam Hussein where the grandson of the Prophet is buried, chanting: "Hussein, Hussein, Hussein." During the ritual, Shi'ites beat their heads and chests and gash their heads with swords to show their grief at Hussein's suffering.

In the past, suicide bombers posing as pilgrims have infiltrated large crowds and militants have fired mortar rounds at the gathering from the outskirts of Kerbala.

Under Saddam Hussein's secular rule, such gatherings were banned in Iraq, which was ruled mostly by Sunnis in his Baath Party.

Since the dictator was toppled in 2003, Shi'ites have dominated Iraqi governments. The newfound right to practice their faith openly en masse in huge annual pilgrimages is an important triumph for the sect but puts them at risk of bomb attacks.

After taking office three months ago, Prime Minister Haider al-Abadi, a moderate Shi'ite, promised to heal sectarian divisions to unite the country against ISIL.

But many Sunnis remain alienated from Baghdad, complaining that there have been no tangible signs that Abadi is taking on Iranian-backed Shi'ite militias, which seem to act with impunity.

Sunnis, who were marginalised by Abadi's predecessor Nuri al-Maliki, say the militias kidnap, torture and kill at will.

The government hopes to win back some support from Sunni tribes to fight ISIL, as the U.S. Marines did against al Qaeda during the "surge" campaign of 2006-2007. But so far, Sunni tribesmen who have stood up to ISIL have paid a heavy price while saying they have yet to receive Baghdad's aid.

Last week, ISIL fighters executed more than 300 members of a Sunni tribe who had defied them in western Anbar province and dumped the bodies in mass graves or on roadsides.

During the emotional ritual in Kerbala, Shi'ites were defiant, despite the new dangers.

"ISIL cannot stop us from coming with their violence," said pilgrim Ali Ajaj, 65.

His wife, Um Mohammed, recalled how Saddam Hussein's agents killed two of their sons, a tragedy that made her more determined to practice her faith.

"ISIL car bombs and explosions will not stop me from coming," she said.

Under strict security measures on Tuesday, cars were not allowed to enter Kerbala for fear of car bomb attacks. Instead, pilgrims boarded buses organised by the authorities.