WASHINGTON--U.S. health officials on Tuesday warned Americans about two potentially deadly Chinese weight-loss pills that may contain fenfluramine, a diet drug pulled from the U.S. market after it was linked to heart problems, Reuter reported.

The food and drug administration said it issued the alert about the Chinese products, Chaso (JIANFEI) diet capsules and Chaso Genpi, because people had died recently in Japan after using them.

Japanese officials have linked various brands of Chinese-made diet pills to five deaths and more than 500 illnesses. a number of the products were found to contain fenfluramine, while others contained thyroid hormones.

The Chaso pills, which are not believed to be on sale in the United States, were banned last month by the Tokyo city government. They were available in stores and on the internet.

"The agency is urging consumers not to take these diet pills and to notify their local FDA if the products are found in their area," an FDA statement said.

The FDA has advised import authorities to be on alert for the two slimming products, the statement said. FDA spokeswoman Laura Bradbard said she did not believe the products had been found in the united states, but "we want consumers to understand it might be brought in unbeknownst to authorities, and we don't want people to buy it."

Fenfluramine had been used in the United States for weight loss with another diet drug, phentermine. The combination was known as "Fen-Phen." Fenfluramine and a related drug, dexfenfluramine, were banned in 1997 after studies showed fen-phen could cause rare but dangerous heart valve defects.

Some later research found no evidence of a high rate of valve damage among people who took Fen-Phen.

phentermine remains on the market.