Pakistan is carrying out an operation targeting people suspected of violence against minority Shi'ites in the southwestern city of Quetta.
Shi'ites in Quetta have been refusing to bury 89 victims of an anti-Shi'ite attack Saturday until the army provides protection.
Prime Minister Raja Pervez Ashraf released a statement Tuesday that ordered security forces to begin the operation, but giving few other details.
The Sunni militant group Lashkar-e-Jhangvi has claimed responsibility for Saturday's bombing, as well as a similar attack last month that killed nearly 100 people.
Sectarian violence claimed more than 400 lives in Pakistan last year.