A Serbian prosecutor said Sunday that a witness has come forward and testified "in detail" about how ethnic Albanian rebels allegedly harvested organs for trafficking from Serbs taken captive during a war in Kosovo, claims Albania and Kosovo have previously denied.

"We have a witness who testified about a medical procedure, done in northern Albania, that consisted of harvesting organs from Serbs kidnapped during the 1998-99 conflict in Kosovo," said Serbia's War Crimes prosecutor Vladimir Vukcevic.

The alleged witness — a former Kosovo Albanian rebel whom Vukcevic did not identify by name — claims to have participated in a surgery involving harvesting a heart from a Serb captive in northern Albania and transporting it to the airport near Tirana, Albania's capital, Vukcevic told the Associated Press.

"We estimate that the information this witness has given is true," Vukcevic said, adding that Serbian prosecutors have been checking the witness' claims for more than a year.

The European Union has launched an investigation into claims of organ harvesting, but it was not immediately clear whether the EU investigation team, led by American prosecutor John Clint Williamson, was familiar with the alleged testimony. Vukcevic said he expected "that the witness' testimony will help prosecutor Williamson's probe."

The EU probe followed a 2010 Council of Europe report by Swiss politician Dick Marty, who alleged that the rebel Kosovo Liberation Army ran detention camps on Albania's border during Kosovo's war for independence from Serbia. The report alleged that civilian captives were killed there and their organs sold as part of illegal trade linked to senior KLA commanders, including Kosovo's Prime Minister Hashim Thaci.

The Council of Europe is based in Strasbourg, France, and includes 47 states from Europe, not all of which are members of the EU. Both Albania and Kosovo have denied the allegations in the report, saying they were orchestrated by Serbia to undermine Kosovo's 2008 declaration of independence.

Vukcevic said the alleged witness has told Serbia's investigators that the captives' organs were sold on the black market. He said the witness is being held in Serbia under strict protection.

About 10,000 people died in Kosovo's 1998-99 war for independence before NATO intervened to force Serbia to end its brutal crackdown against Kosovo separatists and pull its troops out of the territory.

Serbia has vowed never to recognize the independence of its former province, which many Serbians consider their nation's heartland.