consumer group petitioned the federal government yesterday to take the popular weight-loss drug Meridia off the market after 19 deaths were reported as possibly related to the prescription medication.

The drug's manufacturer, Abbott Laboratories, disputed the figures, saying that the deaths had not been proved to be related to the drug and that in any case the number would represent a very small percentage of the nine million people who have taken the drug worldwide since it went on the market in 1998.

Melissa Brotz, a spokeswoman for Abbott, said the drug was important because obesity is a major cause of sickness and death, and even modest weight changes can reduce the risk. Studies have shown that obese people taking the drug have lost an average of 6 to 11 pounds in the first year of treatment, depending on the dose.

Public Citizen, the consumer group found by Ralph Nader, submitted its petition to Secretary Tommy G. Thompson of the Department of Health and Human Services, saying the drug's benefits were minimal — the loss of a few pounds over a relatively short period — and the risks had proved substantial.

More generally, the petition challenged the Food and Drug Administration's approval of weight-loss drugs, suggesting that obesity is a chronic disease but the drugs approved to treat it give only small benefits over a year or two at most.

"No drug ever approved for weight loss has been shown to benefit patients years later," said Dr. Sidney Wolfe, director of the Health Research Group at Public Citizen.

From the time it was first marketed, Meridia, whose scientific name is sibutramine, has been known to cause a sharp rise in blood pressure and pulse rate in some people. An advisory committee to the drug agency voted against approval of the drug, as did the agency's officer in charge of its review for the market, the petition said.

When approval was granted, the drug agency required a warning on the label, along with a recommendation that doctors give patients blood- pressure tests before prescribing the drug. It is unclear whether doctors are following the suggestions.

In the petition, Dr. Wolfe noted that the Food and Drug Administration had reports, as of September 2001, of 357 serious adverse reactions possibly linked to the drug, including 152 hospitalizations and 29 deaths. Of the deaths, 19 listed the cause as cardiovascular disease like high blood pressure or stroke.

The deaths and adverse reaction reports are collected by the drug agency from voluntary reports, and the number of actual incidents is usually estimated to be tenfold higher. The listing of a death in the agency's files means that the drug is a suspect in the case, but that an investigation of the link has not been done.

"Taking only those deaths with cardiovascular causes, the risk is still far too high to allow a drug with such minimal value to be on the market," Dr. Wolfe said.

Italy has suspended sales of Meridia after two deaths were reported in recent weeks, Ms. Brotz said, but Italy is now reconsidering.

Dr. Louis Aronne, assistant professor at Weill-Cornell Medical Center in New York, a researcher who has worked with Abbott, said it was difficult to separate the effects of severe obesity from the side effects of the drug, because both can lead to cardiovascular damage.

On the question of small amounts of weight loss, Dr. Aronne said he suspected that the first 5 percent to 10 percent loss might be the most important. Although the data is unclear now, he added, "we are eventually going to see long-term benefits."