MUMBAI: Dr Reddy's Laboratories Ltd, India's second-largest drugmaker by sales, received a warning letter from the U.S. Food and Drug Administration over inadequate quality control procedures at three manufacturing plants in India. Dr Reddy's shares fell as much as 12 percent in early trade to their lowest level since July 30. The warning letter was issued by the FDA to Dr Reddy's on Thursday for its Srikakulam, Miryalaguda and Duvvada drug manufacturing plants - all based in southern India.