KARBALA (Reuters) -- Overnight clashes between Polish and Bulgarian troops and Shi'ite militiamen in the shrine city of Karbala killed 15 Iraqis, and six Iranian pilgrims were shot dead at a Polish checkpoint, police and doctors said on Friday. The violence on the edge of the southern city erupted a day before millions of Shi'ites are expected to converge on Karbala for the Shi'ite holy day of Arbain.
The U.S.-led administration has warned it cannot guarantee the safety of pilgrims. Suicide bomb attacks during a similar Shi'ite religious event last month killed 171 people.
The overnight clashes between foreign troops and followers of Moqtada al-Sadr, a radical cleric whose militiamen are fighting U.S.-led occupation troops in several Iraq cities, also wounded 21 Iraqis, said Saleh Mahdi, head of Kerbala's health department.
The six Iranians were killed on the road between Babel and Karbala as their car approached a Polish checkpoint, a Karbala police spokesman said. Five Iranians were killed in a similar incident earlier this week.
U.S. troops are fighting on two fronts in Iraq against Sunni guerrillas and Shi'ite militiamen exactly one year after a U.S.-led invasion toppled Iraqi leader Saddam Hussein.
