After years of denial, China has acknowledged that many of the human organs used in transplants here are taken from executed prisoners and that many of the recipients are foreigners who pay hefty sums to avoid a long wait.

Speaking at a conference of surgeons in the southern city of Guangzhou, Deputy Health Minister Huang Jiefu called for a strict code of conduct and better record-keeping to stem China’s thriving illegal organ trade, state media reported.

"Apart from a small portion of traffic victims, most of the organs from cadavers are from executed prisoners," said Huang, reported the English-language China Daily newspaper Thursday. "The current organ donation shortfall can’t meet demand."

Acknowledgment of what had been an open secret on the Internet, in local magazines and among people waiting for transplanted organs came weeks after China announced tighter oversight of death-penalty cases. Legal experts say requiring the country’s highest court to approve death sentences could reduce them by a third.

While China doesn’t disclose the number of people executed each year, Amnesty International reports that at least 1,770 people were put to death in 2005, based on Chinese media reports. Some activists say it could be as many as 10,000.

Even the lower estimate represents more than 80 percent of the 2,148 executions reported to have taken place worldwide last year. The United States executed 60 prisoners.

In July, China ruled that all sales of organs were illegal. But enforcing such decrees can be a problem here, especially when there are such profits.

In September 2004, local media reported that well-known comedian Fu Biao spent more than $36,000 on a liver taken from an executed prisoner in Shandong Province. And starting in June 2005, reports surfaced on the Internet of retinas and kidneys taken from executed former gang members in Henan province near Beijing.

Americans are among the foreigners who have headed to China for transplants as the waiting time for kidneys and livers has grown in the United States. U.S. transplant doctors say the majority seem to be patients of Chinese ancestry who feel comfortable navigating the medical system there.

One was Mabel Wu, 69, of Northridge, Calif., who received a kidney in July at the Hemodialysis and Organ Transplantation Center of the Taiping People’s Hospital in Dongguan, a city in Guangdong province.

Dr. Gabriel Danovitch, Wu’s kidney specialist at the University of California, Los Angeles, refused to endorse her decision.

"I have concerns and suspicions about who those donors are and what consent might have been involved," he said, also voicing concern about the quality of medical care.

The family paid about $40,000 for the surgery. They were told only that the donor was a 30-year-old male.

Wu said there were four other patients at the hospital, all from Taiwan, recovering from kidney transplants when she was there. She flew back to California 12 days after the surgery.

"I am very happy with this transplant," Wu said Friday. "I got a good kidney."

A Chinese transplant doctor, Dr. Zhonghua Chen, said at a conference in Boston in July that Chinese doctors had transplanted 8,102 kidneys, 3,741 livers and 80 hearts in 2005.

Some experts estimate that well over 90 percent of all organs transplanted in China come from executed prisoners, given the limited supply of other organs. China has no system of voluntary donor cards. Furthermore, experts say, because China defines death as a cessation in heart rather than brain-stem activity, there’s little opportunity to recover organs from other sources.

A doctor at Beijing’s Tongren Hospital, who only gave his family name of Wang, said that until recently the hospital had numerous advertisements about buying and selling organs. Shortly after the new rules were announced, the hospital cleaned them up, he said.

Some 2 million Chinese need transplants each year, according to state media, but only 20,000 receive them.