At least 47 people, including six policemen, died after gunmen fired and threw grenades at an emotionally-charged procession of Muslims from the Shia minority on Tuesday, sparking mob violence and rioting.

The attackers struck on the Shia calendar's holiest day, Ashura, coinciding with multiple assaults on Shia shrines in Iraqi cities that killed 140 pilgrims.

The burials in Quetta were delayed by a day because Shia leaders demanded authorities first release Shia youths arrested over the rioting and that they suspend security officials for failing to protect the Ashura procession.

"We have decided to go ahead with the mass funerals today," local Shia leader Jawad Esar told reporters.

Quetta, a dusty city of around one million people including many Afghans, lies 100 kilometers (62 miles) from the Afghan border and 760km southwest of the capital Islamabad.

Its streets have been deserted except for army patrols under a curfew imposed since Tuesday. Authorities said they would lift it temporarily for the funerals.

An inquiry headed by a high court judge has been set up by the provincial Baluchistan government.

Investigators were still trying to clarify the sequence of events and exactly how many attackers were involved.