US authorities decided to put a stop to all the imported blood-thinners. The maufacturers were alerted to test the products against contaminants that may cause serious diseases.

"This alert tells investigators to pay special attention to all heparin products headed for entry in the US," said Janet Woodcock, director of the Food and Drug Administration's (FDA) Center for Drug Evaluation and Research.

"They would be stopping all heparin products for import and ensuring that manufacturers are testing them or we will be testing them ourselves," she said in a telephone press conference.

The FDA on March 5 said it had detected an unidentified contaminant in heparin injections sold by Baxter International pharmaceuticals.

It was determined that most of the active ingredients in the drug came from a plant in Changzou, China working with Wisconsin-based Scientific Protein Laboratories, which supplies Baxter, Woodcock said.

On February 11, the FDA announced a limited recall of Baxter's multi-dose heparin, and on February 28 the lab expanded the recall to include nearly all injectable heparin being produced.

Although the Chinese plant agreed not to export their heparin products to the United States, the FDA issued the alert to "detain all heparin products they might ship in the future," Woodcock said.

She also said the FDA received commitments from five other top manufacturers of injectable heparin "to test their active pharmaceutical ingredient for potential contamination" using two sophisticated, FDA-recommended tests.