Covidien in January said it would recall all production lots of its Duet TRS units, after it received reports of 13 serious injuries and three deaths.

The U.S. Food and Drug Administration said the company had received numerous complaints related to the use of the product since May 2009.

Covidien, however, did not initiate a corrective and preventative action until Jan 19 this year, when an FDA inspection team sought to review data related to the complaints, the regulator said in a warning letter.

The company also failed to document investigations into the deaths and serious injuries, the FDA said in the letter dated June 14.

"Failure to promptly correct these violations may result in regulatory action being initiated by the FDA without further notice," the FDA wrote.

Covidien should investigate and determine the causes of the violations, and take prompt actions to correct the violations and bring the products into compliance, the regulator said.

(Reporting by Shailesh Kuber in Bangalore; Editing by Saumyadeb Chakrabarty)

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