THE HAGUE, Netherlands -- Medical and police authorities are launching a major international probe into the illegal trafficking in human organs for transplants, to help clamp down on the crime, one of the researchers said Thursday.

Frederike Ambagtsheer, of the Erasmus Medical Center in Rotterdam, said a three-year probe now aims to map out the trade and the involvement of criminals in the trafficking.

"Our goal is not to get hard numbers," Ambagtsheer told The Associated Press in a telephone interview. "What we want to do is research the supply and demand and the involvement of organized crime -- who is facilitating these transplants and how?"

Criminal gangs are likely exploiting a situation where demand for donor organs is outstripping supply and patients are left languishing on official transplant waiting lists.

"Because of the scarcity of organs, they become more valuable and therefore more lucrative to trade," Ambagtsheer said.

Organizations in Romania, Sweden, Bulgaria and Spain are also involved in the new project along with the European police organization Europol, the United Nations and European transplant organizations.

In one of the most high-profile and best-documented examples of organ trafficking, in June a European Union prosecutor in Kosovo indicted a Turkish and an Israeli national for involvement in an international ring that duped poor people into donating kidneys that were transplanted into wealthy buyers. The suspects are still at large.

The indictments are part of a larger investigation into allegations that an organized criminal group conducted operations in a clinic outside of the capital Pristina where the victims' organs were transplanted into the buyers.

EU prosecutor Jonathan Ratel said victims were promised up to $20,000 (C14,000) for their kidneys, but were never paid, while recipients were required to pay between C80,000 and C100,000 ($115,000-$143,000).

The victims came from Moldova, Kazakhstan, Russia and Turkey, and lived in "extreme poverty or acute financial distress," the EU law-enforcement mission in Kosovo said.

The trade is not confined to Europe.

A New York man pleaded guilty last year to what experts said was the first ever proven case of black-market organ trafficking in the United States.

Levy Izhak Rosenbaum admitted in federal court in Trenton that he had brokered three illegal kidney transplants from people in Israel for U.S.-based customers in exchange for payments of $120,000 or more. He also pleaded guilty to one count of conspiracy to broker an illegal kidney sale.