EpiPen auto-injection epinephrine pens manufactured by Mylan NV pharmaceutical company for use by severe allergy sufferers are seen in Washington, U.S. August 24, 2016. REUTERS/Jim Bourg/File Photo

(Reuters) - Pfizer Inc said on Thursday it received a request for documents as part of a U.S. investigation related to quality issues involving the manufacture of auto-injectors at its Meridian Medical Technologies site.

Pfizer, in a regulatory filing, said it would be producing records in response to the civil investigative demand from the U.S. Attorney’s office for the Southern District of New York.

Meridian, a unit of Pfizer that manufactures EpiPen injectors used to deliver an emergency allergy antidote, has been hit by a series of manufacturing problems in recent years. Mylan NV, which markets EpiPens, has recalled tens of thousands of the devices after complaints that some had failed to activate.

In 2017, Meridian had received a warning letter from the Food and Drug Administration. The FDA said Meridian had failed to thoroughly investigate product failures, including EpiPen products that were associated with patient deaths and severe illnesses. It said the company failed to take corrective actions until FDA’s inspection.

Meridian produces all EpiPens sold globally at a single plant near St. Louis, Missouri.

EpiPen auto-injectors deliver a dose of epinephrine in the event of severe allergic reaction, such as to bee stings or exposure to peanuts.