THE United States Health and Human Services Sec retary Tommy Thompson and Food and Drug Administration chief Mark McClellan have announced the ban on dietary supplements containing ephedra and alkaloids.

Speaking to newsmen, Thompson said that based on the "best possible scientific evidence" and more than 16,000 incident reports saying ephedra caused adverse effects, the government deduced the product presents an "unreasonable risk to the public health."

Ephedra, known as Ma huang, Chinese Ephedra and epitonin, poses health hazards ranging from high blood pressure, irregular heart-beat, nerve damage, injury, insomnia, tremors and headaches to seizures, heart attack, stroke and death, the FDA says. Ephedra has been linked to as many as 100 deaths, officials have said.

McClellan said his agency was concerned about young people and athletes looking to ephedra to boost their performance. Use of the supplement has led to serious health effects, he said. The rule will go into effect in 60 days "and have the practical effect" of banning ephedra, he said.

The ban is likely to be met with litigation from manufacturers who dispute the agency's assertion that ephedra is a health risk.

The FDA would issue a consumer alert about products containing ephedra, "warning everyone of the dangers they pose," Thompson said.

Ephedra, which has also been used by many athletes to enhance performance, is believed to have killed the Baltimore Orioles baseball player Steve Bechler last February. Bechler died during spring training while trying to lose weight. Toxicology tests showed ephedra was in his system.

The government ban, one of the first involving a dietary supplement, comes after Thompson urged Congress this summer to require manufacturers to acknowledge potential side effects and to rewrite a law that rolled back dietary-supplement regulations.

However, executives of several companies that make ephedra-based products said studies have proven that they are safe when used properly.

"Anyone who has read our label knows that we go to great lengths to inform our customers about the proper use of our products," said Russell Schreck, CEO of San Diego-based nutritional supplement-maker Metabolife International.

Scientists have said it's impossible to prove whether ephedra is safe, because studies screen out participants who have health problems -- the people most likely to be hurt by the products.

"It's a dead product, and unfortunately it has become a dead product over the backs of a lot of dead people when the FDA could have acted before," said Dr. Sidney Wolfe of the consumer advocacy group Public Citizen , which petitioned the government for a ban in 2001.

The supplement industry's Council for Responsible Nutrition said it didn't oppose a ban, noting that very few companies still make the drug.