In a major crackdown against the manufacture of substandard drugs, central and state regulators conducted joint inspections at 76 pharma companies and cancelled the licences of 18 of them for producing spurious and adulterated drugs, official sources said on Tuesday.

The inspections were carried out across 20 states and Union territories in the past 15 days, they said. The names of the companies are not yet known.

An official source said that the action has been taken against 76 companies in the first phase of a special drive against the manufacture of spurious drugs.

"Licences of 18 pharma companies have been cancelled for manufacturing spurious and adulterated drugs and for violating GMP (good manufacturing practice).... Besides, 26 firms have been given show-cause notices and the product permission of three firms have been also cancelled," the source said.

As part of the special drive, the regulators have identified 203 firms. A majority of the companies are from Himachal Pradesh (70), followed by Uttarakhand (45) and Madhya Pradesh (23), sources said.

More such inspections will follow in the coming days, they said.

Recently, questions have been raised over the quality of drugs manufactured by India-based companies. In February, the Tamil Nadu-based Global Pharma Healthcare recalled its entire lot of eye drop allegedly linked to vision loss in the US.

Before that, India-made cough syrups were allegedly linked to children deaths in the Gambia and Uzbekistan last year.