UPDATE 3-US orders stronger overdose warning on painkillers

* FDA wants stronger warning on Darvon, Darvocet

* Agency rejects call to ban the painkillers

* Advocacy group says FDA decision "reckless" (Adds advocacy group's reaction)

WASHINGTON, July 7 (Reuters) - U.S. regulators on Tuesday ordered stronger warnings about overdoses with the painkilling drugs Darvon and Darvocet and rejected a consumer group's call for a ban of the medicines.

The action applies to drugs made with propoxyphene, the decades-old pain-killing ingredient in privately held Xanodyne Pharmaceuticals Inc's Darvon and Darvocet and generic medicines.

The Food and Drug Administration said it was requiring tougher, boxed warnings on the medicines because of reports of accidental and intentional overdoses, including some that were fatal.

"FDA is taking action to reduce the likelihood of such fatal overdoses in the United States while we investigate the safety of propoxyphene more fully," an agency statement said.

But Dr. Sidney Wolfe, head of the Health Research Group at Public Citizen, which petitioned the agency for a ban, said such labeling was insufficient for a drug that has been linked to more than 2,000 deaths.

"It really is a reckless decision," said Wolfe, adding that his advocacy group is considering further legal action, as well as a formal appeal to FDA Commissioner Dr. Margaret Hamburg.

Health officials in the United Kingdom banned propoxyphene in 2005 and European regulators are also considering taking action, he added.

The FDA said it rejected a ban because the benefit, "of using the medication for pain relief at recommended doses outweighs the safety risks at this time."

Propoxyphene, a type of opioid painkiller, has been on the market since 1957.

FDA officials acknowledged recent evidence in Europe that the drug could be "more lethal in overdose than other pain medications," adding that the agency would continue to evaluate the safety of propoxyphene and take additional action if necessary.

The FDA is also requiring a new study to evaluate the drug's effects on the heart at higher-than-recommended doses.

Consumer group Public Citizen petitioned the FDA in 2006 to order a phased withdrawal of propoxyphene and an agency advisory panel voted 14-12 in favor of pulling products containing the drug from the market.

A Xanodyne official had no immediate comment. (Reporting by Lisa Richwine and Susan Heavey, editing by Richard Chang and Andre Grenon)