Pilgrims flagellate themselves with knives attached to chains during an Ashura procession in Kerbala, 110km (70 miles) south of Baghdad, Iraq, yesterday. Tens of thousands of Shi'ite Muslims are expected to gather in Kerbala this week to celebrate a religious festival called Ashura, the day when Imam al-Hussein, the 'leader of the martyrs' and grandson of Prophet Mohammad, was killed in Kerbala in AD 680. - Reuters

NAJAF (Reuters):

United States and Iraqi forces killed some 250 gunmen from an apocalyptic Muslim cult yesterday in a battle involving U.S. tanks and aircraft near the Shi'ite holy city of Najaf, Iraqi police, army and political sources said.

Two Americans were killed, the U.S. military said, when an attack helicopter went down during the day-long battle in what was one of the strangest incidents of the four-year conflict. Iraqi officials said the helicopter seemed to have been shot down.

According to one Iraqi political source, hundreds of fighters drawn from both Sunni and Shi'ite communities were still fighting. A Reuters reporter at the scene, 160km (100 miles) south of Baghdad, saw U.S. tanks and heard blasts after dark and an Iraqi officer said F-16 jets were bombing the area.

Details of the day's fighting were sketchy and the origins of the fighters unclear. An Iraqi army source said some of the dead wore headbands declaring themselves 'Soldiers of Heaven'.

The governor of Najaf province said the group had gathered in orchards near the city and had been planning to attack the main Shi'ite clerical leadership on Monday. It is the climax of the annual Shi'ite rite of Ashura, marking a seventh-century battle which entrenched the schism between Shi'ite and Sunni Islam.

Earlier, the governor described the fighters as Sunnis, the majority in the Arab world and the once dominant minority in Iraq, where Shi'ites have been in the ascendant since the U.S. invasion of 2003. The two sects are embroiled in conflict that many fear is descending into all-out civil war.

But political and security sources said they were followers of Ahmed Hassani al-Yemeni and described him as an apocalyptic cult leader claiming to be the vanguard of the Mahdi - a messianic figure in Islam whose coming heralds the start of perfect world justice. He had been operating from an office in Najaf until it was raided and closed down about 10 days ago.

Similar violent cults

Similar violent cults have been a feature of Islamic history. They have declared temporal Muslim leaders illegitimate infidels and have drawn followers from both Sunni and Shi'ite believers, proclaiming a unity of inspiration from Mohammad.

Hundreds of thousands of Shi'ite pilgrims were gathering in the holy city of Kerbala, between Najaf and Baghdad, to mark Ashura - the death of Mohammad's grandson Hussein in the Battle of Kerbala in AD 680, which confirmed the split in Islam between supporters of rival claimants to the prophet's inheritance.

In Baghdad, 13 people were killed in bombings in mainly Shi'ite areas, police said. In a Sunni area, five girls were killed when a mortar struck their schoolyard.

Twin car bombs targeting ethnic Kurds killed 16 people as night fell in the northern oil city of Kirkuk, whose population is a volatile mix of Kurds, Turkmen and Sunni and Shi'ite Arabs.