KEY POINTS:
Mariam Karouny and Alastair Macdonald
BAGHDAD - US forces had one of their costliest days in Iraq on Saturday when 21 troops were killed, including 13 in a helicopter and five in a clash in a Shi'ite holy city the US military said was triggered by militiamen.
The battle at a government building in Kerbala was the bloodiest for US troops in the Shi'ite south in two years and occurred as President George W. Bush presses leaders of the Shi'ite majority to crack down on militias from their community.
Hours after reporting three deaths in separate incidents and the loss of all 13 passengers and crew aboard a Blackhawk transport helicopter, the US military said five soldiers were killed and three wounded in the Kerbala clash.
It was the deadliest day for US forces since Bush announced 10 days ago he was sending about 20,000 troops to Iraq to try to prevent sectarian civil war between Shi'ites and the once- dominant Sunni Arab minority. His plans have run into resistance from opposition Democrats who now control Congress.
It was unclear whether the helicopter was shot down. Residents in violent Diyala province northeast of Baghdad said they saw a helicopter in flames in the air.
The Kerbala clash occurred as thousands of pilgrims thronged through the city, 110 km south of Baghdad, at the start of the 10-day rite of Ashura, a highpoint of the Shi'ite Muslim calendar.
"The Provincial Joint Coordination Center (PJCC) in Kerbala was attacked with grenades, small arms and indirect fires by an illegally armed militia group," the US military said in a statement, apparently blaming Shi'ite militiamen rather than Sunni insurgents whom it usually calls terrorists.
"Five US soldiers were killed and three wounded while repelling the attack," said the statement.
An Iraqi local government official who said he was in the building throughout questioned the identification of those who fought the US troops posted outside a joint US-Iraqi base, in the provincial governor's headquarters, just after dark.
Describing how a convoy of half a dozen white, US-made, unmarked four-wheel drive vehicles approached the compound round 6pm (4am NZT), he said armed men in the convoy exchanged heavy fire with US soldiers.
US troops and Iraqi special forces later searched the office of the governor and other senior officials, said the official, who represents a major Shi'ite political party and spoke to Reuters on condition of anonymity.
"It's still very mysterious," he said. "I'm not sure why they say those people who came in were militia. The police on duty said they thought they were Americans."
Relations have become strained between Washington and Shi'ite-led Iraqi government as the United States presses Baghdad to rein in Shi'ite militias blamed for death squad killings and tries to limit the influence of Shi'ite Iran.
Not since US troops fought street battles with the Mehdi Army of radical Shi'ite cleric Moqtada al-Sadr in southern Iraq in 2004 have US forces had such heavy casualties in the region.
- REUTERS
