Taiwan detected cattle feed additive zilpaterol in U.S. beef, the third such incident in less than a month in Asia, heightening concerns across the region over banned animal growth drugs.

Taiwan's Food and Drug Administration said on Tuesday it found the beef tainted with the growth enhancer in a restaurant owned by Wowprime Corp., prompting authorities to increase checks on U.S. meat imports. An official at Wowprime said it had destroyed all of the 203 kg of tainted U.S. beef.

There is zero tolerance for feed additives such as zilpaterol in much of Asia and Europe due to concerns about the side effects of such drugs, which are used to add muscle weight to animals.

Feed additives have been the focus of attention since a video appeared in the United States in August showing animals struggling to walk and with other signs of distress after taking a growth drug.

South Korea suspended some U.S. beef imports after detecting zilpaterol in meat supplied by a unit of JBS USA earlier this month and authorities in Taiwan found U.S. meat with the same drug.

The detection of the additive has raised concerns that it may still be in the supply chain despite drug maker Merck & Co. halting sales of Zilmax, the top-selling zilpaterol-based additive, on August 16.

The U.S. Department of Agriculture has said a Swift Beef Company plant in Cactus, Texas, is not eligible to ship beef to South Korea after the country detected growth drug in meat supplied by the company.

Zilpaterol is a beta-agonist, a kind of feed additive that can add as much as 30 pounds of saleable meat to an animal in the weeks before slaughter.

Originally developed as asthma drugs for humans, beta-antagonists - in a decade of use - have helped bolster the ability to produce more beef with fewer cattle in the United States.

Ever since the video of distressed cattle appeared, the Chicago Mercantile Exchange has said it will no longer accept delivery of cattle fed Zilmax to conform with exchange guidelines for deliveries against CME live cattle futures.