MANILA, Philippines — Foreigners will be permanently banned from receiving kidneys for transplant in the Philippines to prevent the country from becoming a major Asian center in an already thriving black-market trade, health officials announced today.

Extensive kidney trading involving impoverished Filipinos and prisoners — who sell their organs for paltry sums to syndicates catering mostly to foreign clients — has been reported by the local media in recent years.

A temporary ban was recently imposed on kidney transplants involving foreigners.

"Today, the Philippine government asserts its mandate to protect the poorest and most vulnerable sectors of our society," Health Secretary Francisco Duque said in announcing the ban.

China and Pakistan, among the world's biggest sources of kidneys, have taken steps to outlaw the sale of human organs, and desperate foreigners may be prompted to increasingly turn to the Philippines, he said.

"The sale of one's body parts is condemnable and ethically improper. We have to stop it," he said.

The sale of organs is illegal in the Philippines. The ban — intended to protect poor Filipinos from exploitation — will prohibit foreigners from getting donated kidneys unless they can prove a donor is related to them by blood, Duque said.

He said the ban was endorsed by President Gloria Macapagal Arroyo and will take effect in about three weeks. Kidney donations among Filipinos will continue but will be strictly monitored by a new regulatory body, he said.

Social Welfare Secretary Esperanza Cabral said at least 500 kidney transplants involving foreign patients were conducted last year in the Philippines.

The kidney trade, often in the guise of donations, has long thrived in the country in secrecy, fostered by syndicates that lure the poor to sell their kidneys to foreigners, mostly from Japan, Europe and the Middle East, officials say.

Two weeks ago, police raided a house near Manila and rescued seven men who were lured by a gang that promised them jobs but later forced them to agree to become kidney donors.

The gang was still searching for foreign clients when the seven were freed. Two other men in the house had already lost their kidneys, police Superintendent Antonio Yarra said.

Local TV networks have shown footage of Manila slums where virtually all men bore surgery scars after selling their kidneys for about 200,000 pesos (US$4,760; euro3,000) each.

Cabral has said a permanent ban on kidney transplants for foreigners can help authorities more easily eradicate the thriving black market.

Many Philippine donors have developed ailments such as urinary tract infections and high blood pressure linked to the transplants because of a lack of post-operation care, Cabral said.