HONG KONG — China said Tuesday that it was investigating whether 17 Japanese tourists had received illegal kidney and liver transplants in China.

China has banned all transplants for foreigners — so-called organ tourists — because an estimated 1.5 million Chinese are on waiting lists for transplants. The ban was issued May 1, 2007.

"China strongly opposes organ transplant tourism," the Ministry of Health said in a statement on its Web site, adding that the hospitals and medical personnel "who carried out the organ transplants against the rules will be severely dealt with according to the law."

It was not immediately clear whether news of the investigation would increase anti-Japanese sentiment in China. Relations between the countries can be fragile, with old wounds still sensitive.

The ministry's investigation, reported in the state-run newspaper China Daily, comes after the Japanese news agency Kyodo News reported that the 17 tourists had spent $87,000 each for the operations. The price included travel, accommodations and 20 days of treatment at a hospital in Guangzhou, in southern China, the report said.

At the request of the hospital, some of the Japanese patients registered under Chinese names, the Kyodo report said. Most of the patients were between 50 and 65 years old.

The news agency also said most of the organs were likely from executed Chinese prisoners.

Chinese officials have said the state uses only prisoners' organs that have been voluntarily donated. Courts, doctors, health officials and hospitals must approve such transplants, and the prisoners must agree in writing, the government said.

China Daily reported that China was second only to the United States in the number of transplant operations done each year.

"Due to the lack of organ donors, shortage of organs is a problem in all countries, not just China," Mao Qunan, a Health Ministry spokesman, said at a recent press briefing. "Priority must be given to domestic patients in urgent need of an operation."

Last year the deputy health minister, Huang Jiefu, said his ministry had punished three Chinese hospitals for selling organs to foreigners. The disclosure, reported in local media, came in remarks Mr. Huang made at a medical conference in Shanghai.

An investigation in China in 2004 by the British newspaper The Independent found a flourishing underground trade in organ sales and transplants, especially for Japanese patients. And in 2006, a BBC reporter went to a public hospital in the city of Tianjin, ostensibly to arrange a liver transplant for his ailing father. The reporter said hospital officials told him a suitable liver could be available in three weeks.

Earlier this month, after years of controversy over organ trafficking in China, the government said it would establish a registry for organ donors and recipients.