Updated

The U.S. Food and Drug Administration took 684 days to issue a warning letter after uncovering serious issues at the pharmacy at the center of the deadly U.S. meningitis outbreak, newly released documents showed.

The New England Compounding Center (NECC) chastised the FDA for taking so long, telling the agency its response time was nearly 18 months longer than the FDA's average response, according to letters released by a Freedom of Information Act request from Reuters.

The FDA issued the warning letter in December 2006. It was based on an inspection of NECC that began in September 2004 and ended on January 19, 2005, according to the documents.

"This prolonged gap between inspection and warning letters does not comply with FDA's procedures," NECC's chief pharmacist, Barry Cadden, wrote in a January 5, 2007 letter to FDA compliance officer Ann Simoneau.

In follow-up correspondence, FDA officials apologized for the "significant delay" in correspondence time between the inspection and the warning letter. While the FDA conceded the gap was unusual, it in no way diminished the regulator's "serious concerns" about NECC's pharmacy operations, documents showed.