WASHINGTON, Feb. 19 (UPI) -- U.S. regulators acknowledge the Chinese firm supplying the active ingredient for Baxter Pharmaceutical's heparin was never inspected due to a name mix-up.

The Food and Drug Administration admitted Monday the firm called Changzhou SPL, west of Shanghai, is similar in name to another Chinese drug manufacturer, which had been inspected, The Washington Post (NYSE:WPO) reported.

The agency plans to visit the plant this week, the Chicago Tribune reported.

Because of the mix-up, the plant ,which began production of heparin's active ingredient in 2004, was never inspected, the agency said.

The FDA said recently that it annually inspects roughly 7 percent of foreign drug companies.

More than 350 adverse reactions to Baxter's version of heparin have been reported this year and 4 deaths have been associated with the drug.

Rep. John D. Dingell, D-Mich., wrote the FDA last week, decrying the "disastrous state of your agency's foreign inspection program related to pharmaceuticals."

Director of field investigations at the FDA's Office of Regulatory Affairs Michael Rogers said the heparin problem was, "one of the agencies top priorities."

FDA Commissioner Andrew C. Von Eschenbach has also asked that the agency open three permanent offices in China.

The cause of the reactions, which include nausea, dizziness and dropping blood pressure, has not been found.