Blast close to Islamabad's Red Mosque, cause unknown

ISLAMABAD (Reuters) - A blast was heard in Pakistan's capital Islamabad on Sunday but the cause was unknown, a Reuters witness said.

Dawn News, a private television channel, reported that the blast was close to a commercial shopping area near the Red Mosque, the scene of a bloody battle between Pakistani security forces and Islamist militants a year ago.

Thousands of Pakistani Islamists vowed support for jihad, or Muslim holy war, on Sunday as they gathered at the mosque to mark the first anniversary of the army raid on the complex.

More than 100 people were killed when commandos stormed the mosque complex, which included a madrasa or Islamic seminary, on July 10 last year, after a week-long siege that began when gunmen from the mosque clashed with police outside.

Speakers told a crowd of several thousand, most of them men, that U.S. ally President Pervez Musharraf was to blame for the bloodshed.