Pakistani officials say faulty heart drugs are thought to have killed around 100 people over the past three weeks.
Dozens more victims were reported in critical condition.
Most of the deaths are reported to have occurred in Lahore, the capital of the central Punjab Province.
Shahbaz Sharif, the head of the Punjab provincial government, said the victims appear to be mostly poor patients who received free locally manufactured drugs for heart disease from the state-run Punjab Institute of Cardiology (PIC).
Police have arrested the owners of three local pharmaceutical companies suspected of supplying the drugs.
Doctors have been quoted as saying more than 40,000 patients receive drugs from the PIC every month.
compiled from agency and media reports