The warning letter follows inspection of the facility in September 2014 by US Food and Drug Administration (USFDA) inspectors.
"Post the September 2014 inspection, the USFDA has withheld future product approvals from the Halol facility. This situation may continue until all issues are resolved.
"Sun Pharma expects to request a re-inspection by USFDA upon completion of its remediation commitments," the company said in a statement.
The firm and the Halol facility will continue to supply important drug products to meet its obligations towards the customers and the patients who use its drugs in the US and around the world, it added.
Commenting on the development, Sun Pharma Managing Director Dilip Shanghvi said, "While our team is working hard to ensure that the commitments made to the USFDA in September 2014 are fully completed, we will continue to cooperate with the USFDA and undertake any additional steps necessary to ensure that the US agency is completely satisfied with our remediation of the Halol facility."
He added: "We are pledged to being cGMP compliant and are committed to continuing to supply our customers and patients across the world with quality products that meet all specifications."
The company has been working with external consultants to ensure its remediation activities have been completed in an appropriate manner, it added.
(REOPENS DCM6)
Later in the day, addressing a conference call, Shanghvi said Sun Pharma's focus is to make the Halol plant cGMP- compliant again and rather than moving products manufactured there to other facilities.
"Major focus is on getting Halol re-certified", rather than protecting cash flow from each small products, he said.
The company will wait for the USFDA to put in public the warning letter, he added.
As per the USFDA, observations are made in form 483 when investigators feel that conditions or practices in the facility are such that products may become adulterated or render injurious to health.
When asked about the impact of the warning letter over the Halol plant, he said did not elaborate but said sales from the plant contributed to the total a "high single digit percentage number on consolidated basis".
