KARACHI -- A suicide bomber attacked a Shi'ite Muslim procession in Pakistan's commercial capital, Karachi, today, killing at least 25 people.
The attack on a Shi'ite march, the third in Pakistan's biggest city in as many days, underscored the multiple security challenges facing the country.
The nuclear-armed U.S. ally is struggling against Al-Qaeda-linked militants and is under pressure from Washington to help stabilize neighboring Afghanistan, where a Taliban insurgency is raging.
The bomb exploded at the end of a procession for Ashura, the Shi'ite calendar's biggest event.
Television pictures showed a big cloud of smoke over the scene and reporters said angry worshippers attacked journalists.
Interior Minister Rehman Malik said at least 25 people were killed and about 50 wounded in Karachi, a major transit point for military and other supplies to Afghanistan for the U.S- and NATO-led anti-insurgency effort.
Malik said extremists wanted to destabilize Pakistan.
"Whoever has done this, he cannot be a Muslim. He is worse than an infidel," he told reporters.
Ashura falls on the 10th day of a 40-day mourning period during the Islamic calendar's first month, Moharram, which commemorates the death of Imam Hussein, a grandson of the Prophet Mohammad, who was killed in battle in A.D. 680 in the Iraqi city of Karbala.
Processions by minority Shi'ite Muslims are often attacked by majority Sunni Muslim militants.