A senior pro-Taliban cleric in Pakistan was gunned down by unknown assailants outside his mosque in the port city of Karachi on Sunday and later died of his wounds, police and hospital sources said.

Mufti Nizamuddin Shamzai, who called for a holy war against the United States after the invasions of Afghanistan and Iraq, was wounded along with three of his sons outside his mosque, police official Fayyaz Qureshi said.

"He has expired," said a source at the hospital to which Shamzai and his sons were taken. "We have not yet announced it because there is a huge mob outside and we are worried about a law and order situation," he added, asking not to be named. It was not immediately clear who was behind the attack.

Shamzai was sympathetic to the Taliban, but bristled at some pronouncements made by al Qaeda leader Osama bin Laden, particularly a statement saying he admired the people who carried out the Sept. 11, 2001 attacks in New York and Washington. "It's wrong to kill innocent people," Shamzai said at the time.

In late September 2001, Shamzai was part of a delegation of Muslim clerics that urged Taliban leader Mohammad Omar to hand over bin Laden to spare Afghanistan from a U.S. military strike. Omar rejected the appeal, speaking at length about the "virtues of going to war with the infidels." The U.S. bombing campaign began a week later.