Federal regulators have issued a warning to blood-testing equipment maker Immucor Inc. for lax manufacturing procedures at a plant in Georgia.

Food and Drug Administration inspectors said they uncovered at least five violations during a visit to the company's Norcross, Ga., factory in January. The site produces chemicals used to screen blood donations. The FDA posted a warning letter to the company on its Web site Tuesday.

Agency inspectors said the company did not have a clear procedure for handling products that did not meet pre-specified standards. In several cases, Immucor released batches of blood tests that had bacterial contamination before completing an investigation.

The FDA also said the company did not have firm procedures for handling product complaints. In one case the company failed to notify the FDA within 30 days of a complaint about a product that could have malfunctioned and caused death or serious injury.

The agency acknowledged that Immucor responded to the inspectors' citations but said "your responses did not provide sufficient detail."

Immucor Chief Executive Gioacchino De Chirico said in a statement the company is "working diligently to respond to FDA as soon as possible." He added that the FDA has not placed any limitations on the company's products or facilities.

The FDA regularly issues warning letters to companies that do not follow regulations for manufacturing and marketing of medical products. The letters are not legally binding, but the agency can take companies to court if the warnings are ignored.

Shares of Immucor Inc. fell $1.61, or 5.8 percent, to $26.35 in midday trading.