LAHORE, Pakistan (AFP) - Around 100 Pakistani heart patients have died after taking faulty medicine made locally and dozens more are in a critical condition in hospital, government officials said Thursday.

"Nearly 100 patients have died due to a reaction to heart drugs," said Shahbaz Sharif, the head of the government in central Punjab province.

The victims were mostly poor patients who received free drugs from the state run Punjab Institute of Cardiology (PIC), he said.

The government said another 287 people had been admitted to hospitals in Lahore, Pakistan's second largest city, after taking the drugs.

Police have arrested owners of three pharmaceutical companies suspected of supplying the medicine.

"Police registered a case on Tuesday after reports of deaths of people due to reaction of drugs for cardiovascular diseases," police spokesman Haroon Rashid told AFP.

Initial investigations show that drugs supplied by local manufacturers were "sub-standard," police said.

The patients died due to a sudden drop in white blood cells, platelets and bone marrow damage.

The problem was first detected in December when contaminated drugs in at least one batch of medicine caused 23 deaths.