The letter concerns the company's finished-drug plants at Piparia in western India, and Indore in central India, as well as the drug ingredients facility at Ratlam in central India, IPCA said in a statement.
The plants have already been banned from supplying to the United States after the FDA inspected them in July 2014, January 2015 and March 2015, and first highlighted the lapses. IPCA said it has since been trying to fix the problems and has been informing the US drug regulator of its remedial measures.
"The company is fully committed to resolving these issues at the earliest," it said, without disclosing the content of the letter. The FDA usually posts such letters on its website a week after issuing them to manufacturers, who need to respond to the agency within 15 days with a plan on how they would work on fixing the issues.
IPCA, a mid-sized Indian firm with 2015 revenue of about $500 million, has 16 manufacturing plants in India from where it supplies to more than 120 countries. The three sites with US bans also supply to India, the UK and Canada.
The FDA warning follows similar action on plants of larger rivals Dr Reddy's Laboratories Ltd and Sun Pharmaceutical Industries Ltd in November and December, respectively.
Several drug factories in India have been cited by the FDA over the last two years for violating manufacturing quality standards, as the US regulator has increased its oversight of the industry, which is a key supplier to the United States.
IPCA's stock fell as much as 16 per cent on Monday in Mumbai. It pared some losses to trade down 5 per cent by 0721 GMT (12:51 p.m. in India), while the broader market was up 0.1 per cent.
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.