Hardline Sunni Muslim groups have stepped up a campaign of bombings and assassinations of minority Shi'ites and, on Saturday, Lashkar-e-Jhangvi (LeJ), seen as the most ruthless Sunni sectarian group, claimed responsibility for the Quetta attack.
Victims of the bombing in the main bazaar were mostly from the Shi'ite Hazara community.
Nawab Zulfiqar Ali Magsi, governor of Baluchistan province, said: "The terrorist attack on the Hazara Shi'ite community in Quetta is a failure of the intelligence and security forces."
Vice president of the Hazara democratic party, Aziz Hazara, said: "We are giving the government 48 hours to arrest the culprits involved in the killing of our people.
"After that we will launch strong protests."
Mohammad Imran, a local trader, said: "If the government wants [to prevent attacks], no-one can take even a kitchen knife into any market."
The death toll from Saturday's bombing rose overnight.
A security official saying the figure could rise, with 20 people still critical.
LeJ has also admitted responsibility for a bombing last month in Quetta that killed nearly 100 people.
Intelligence officials say extremist groups, led by LeJ, want to destabilise Pakistan and pave the way for a Sunni theocracy.
Yesterday, the search for survivors went on beneath rubble and debris while relatives of the wounded responded to an appeal for blood made by hospitals.