Pakistani officials say a suicide bomber has struck a Shi'ite Muslim religious procession in the southern city of Karachi, killing 30 people and wounding dozens of others.

Officials say the bomber blew himself up Monday while walking in a procession of Shi'ites observing the mourning rituals of Ashura in Pakistan's commercial capital.  The blast triggered riots in parts of Karachi, with angry mourners throwing stones and firing weapons into the air.

Despite increased security across Pakistan for the Shi'ite religious observance, the Karachi bombing is the second major attack on minority Shi'ites in as many days.  

A suicide bomber struck a Shi'ite mosque in Pakistani-controlled Kashmir Sunday, killing at least 10 people and wounding more than 80.

The annual Ashura commemoration is the climax of observances during the first 10 days of the Muslim month of Muharram, when Shi'ites mourn the seventh-century killing of Imam Hussein.  In Pakistan, the period is frequently a time of tension between Sunnis and Shi'ites.

Separately, the Pakistani army says troops have killed some 15 militants in the ongoing offensive against the Taliban in the South Waziristan tribal region.

A military statement says the militants were killed when they tried to raid a security checkpoint.  Two soldiers were reported killed.

Some information for this report was provided by AP, AFP and Reuters.