Sun Pharmaceutical Industries, India’s largest drugmaker, said on Saturday that it had received a warning from the US Food and Drug Administration for violating manufacturing standards at its Halol plant in Gujarat. The letter implies that the body is not satisfied with the remedial measures the company implemented since the FDA first pointed out issues at the plant after an inspection last September, Reuters reported.

Although Sun Pharma maintained that it had been updating the agency on the “significant investments” it had made to improve quality systems at the factory, the letter suggests the company is still far from getting FDA clearance and that it could ban all drug imports from the plant unless the issues are fixed.

In a statement issued by the firm, Managing Director Dilip Shanghvi said Sun Pharma was cooperating with the FDA and “willing to undertake any additional steps necessary to ensure that the US agency is completely satisfied with our remediation of the Halol facility.” The company said it would implement measures to tackle the problems highlighted by the FDA and request a re-inspection of the plant once all remedial steps are in effect.

The statement did not mention when exactly the warning letter was issued. Such intimations are usually posted on the agency’s website a week after they are sent to the manufacturer.

Since the inspection last September, Sun Pharma has failed to secure approvals for drugs it makes at the Halol plant. This has affected its sales in the United States, its largest market. Over the past year, the FDA has been cracking down on drug manufacturing plants in India, which supply some 40% of the medicines sold in the US, and has been sending warnings to dozens of Indian firms.