An apocalyptic sect, led by a man claiming to be an Islamic messiah, has been wiped out in Iraq just as it was planning to disrupt the holiest day in the Shia Muslim calendar, Iraqi officials claimed Monday.

Iraqi soldiers, backed by U.S. tanks and helicopters, concluded one of the strangest battles in four years of fighting in the country at dawn Monday morning near the city of Najaf.

Iraqi government officials claimed that as many as 200 militants from a Shia sect calling themselves Jund al-Samaa (Soldiers of Heaven) were killed in fierce fighting that lasted for nearly 24 hours and cost the lives of five Iraqi personnel and two U.S. servicemen whose helicopter crashed. A further 100 rebels were reported captured.

Reports from Najaf today described the city as calm but awash with Iraqi soldiers and roadblocks, ordering men out of their cars and demanding identity papers. A sandstorm enveloped the streets in an orange mist.

Iraq’s national security minister said the leader of the sect was a 40-year-old Iraqi who claimed to be the Mahdi — an Islamic prophet who is destined to rise again and judge good from evil. The man, believed to be from the nearby Shia city of Diwaniya was killed just as he was preparing to lead an attack on Shia clerics in Najaf, Shirwan al-Waeli said.

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"He claimed to be the Mahdi," said al-Waeli, adding that that the man used the full name Mahdi bin Ali bin Ali bin Abi Taleb, claiming descent from the Prophet Muhammad.

"One of the signs of the coming of the Mahdi was to be the killing of the Ulema [Islamic clerical leaders] in Najaf," he said.

Maj. Gen. Othman al-Ghanemi, the commander of the 8th Division that is in charge of Najaf, said the area where the men were staying was once run by Saddam's al-Quds Army, a military organization the late president established in the 1990s.

The commander said "the gunmen had recently dug trenches in preparation for the battle." He added that the area of full of date-palm groves. Other officials in Najaf said Saddam loyalists bought the groves six months ago.

Al-Ghanemi said 600 to 700 gunmen had planned to disguise themselves as pilgrims and attack Najaf on Tuesday, the day they believed that the Imam Mahdi, or the "hidden imam," would reappear. He said leading Shiite ayatollahs consider such fringe elements as heretics.

Their aim was to kill as many leading clerics as possible, al-Ghanemi said. The army captured some 500 automatic rifles in addition to mortars, heavy machine guns and Russian-made Katyusha rockets in what amounted to a major test for Iraq's new military as it works toward taking over responsibility for security from U.S.-led forces.

Najaf government officials indicated the militants included both Shiite and Sunni extremists, as well as foreign fighters.

Sectarian attacks have accompanied Ashoura, the holiest festival in the Shia calendar, in each of the last three years in Iraq, including the deadly, synchronized bombings of shrines in 2004 that cost nearly 200 lives.

The festival, during which devout Shia flagellate themselves, causes tension between Sunnis and Shia because it commemorates the 7th-century death of the Prophet Muhammad’s grandson, Imam Hussein, that led to the schism between the two main strains of Islam.

But the violence has typically been perpetrated by Sunnis on Shias and vice versa, not because of splits within the communities.

So there was confusion today about the origins and motives of the sect. U.S. officials have declined to comment on the battle, saying the operation was still continuing but the deputy governor of Najaf claimed that the group was a Shia cult linked to Al Qaeda and had foreign fighters within its ranks.

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Iraqi military officials said that 30 of the dead were Afghans and Saudis and that of the 13 arrested, one was from Sudan.

The role of Al Qaeda is unclear, because the group has typically allied itself with extremist Sunni militants, regarding Shia Muslims as apostates and heretics. The deputy governor of Najaf, Abdel Hussein Attan, said the militia "appears to be a Shia group but its deep-rooted conviction is different".

"I have come to the total conviction from what I have seen with my own eyes on the ground that Al Qaeda is behind this group," he said. "Based on the confessions of interrogated militants and other information, this well-structured group intended to attack Shia clerics and take control of Najaf and its holy sites."

The Associated Press contributed to this report.