Following reports, Sun Pharma shares dipped over 4%.
The financial impact of the alert is yet to be known.
An "import alert" results in the detention without physical examination of drugs from firms that have not met so-called good manufacturing practices, according to the FDA website.
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Sun Pharma's shares had also fallen earlier this week after the company had withdrawn bottles of diabetes drug from the US market. Sun's Detroit-based subsidiary Caraco Pharmaceutical Laboratories recalled 2,528 bottles of Metformin HCL, a drug meant to treat Type 2 diabetes, after a customer complained of finding tablets of Gabapentin, an epilepsy drug, in a bottle.
The US Food and Drug Administration classified the recall as "Class II," which signifies a remote chance of severe adverse consequences or death due to the product flaw.
The company's stock had underperformed the market over the past one month till 10 March 2013, falling 2.52% compared with the Sensex's 7.87% rise. The scrip has also underperformed the market in the past one quarter, rising 1.49% as against Sensex's 3.2% rise.
Other pharma majors like Ranbaxy and Wockhardt are already under USFDA scanner following various import alerts.