The report by Council of Europe investigator Dick Marty, two years in the making, suggests Kosovo's U.S.-backed prime minister was once the "boss" of a criminal underworld behind the grisly trade.
The report, which cites FBI and other intelligence sources, has been obtained by the British newspaper the Guardian. It names Kosovo's Prime Minister Hashim Thaci as having over the last decade exerted "violent control" over the heroin trade.
According to the Guardian, members of Thaci's inner circle are accused of secretly taking captives across the border into Albania after the war, where a few Serbs are said to have been murdered for their kidneys, which were sold on the black market.
The alleged crimes occurred after the Kosovo war ended in 1999.
Marty's investigation of the KLA's alleged trade in organs stemmed from a book by U.N. War Crimes tribunal prosecutor Carla Del Ponte, based on information she said she received from Western journalists.
Kosovo's government Tuesday branded the report an attempt "to tarnish the image of the Kosovo Liberation Army."
Marty, the human rights investigator behind the inquiry, will present his report to European diplomats from all 47 member states at a meeting in Paris on Thursday, the Guardian reports.
Also on Tuesday, a prosecutor charged seven Kosovans on trial in Pristina were part of the network that traded organs.
European Union Prosecutor Jonathan Ratel told the crowded Pristina District Court that the men, including a former senior Health Ministry official, promised poor people from Moldova, Kazakhstan, Russia and Turkey up to $20,000 for their organs.
Those who received the organs - including patients from Canada, Germany, Poland and Israel - paid between $110,000-$137,000 for them, Ratel said. The victims, however, were never paid, he added.
The prosecutor, who serves in Kosovo as part of the EU's rule of law mission, alleged that what he called an organ-harvesting ring recruited about 20 foreign nationals with false promises of payments in 2008.
The seven men have pleaded not guilty to charges ranging from trafficking in persons to unlawful practices of medicine and abuse of power. None of them is in custody. Two other suspects, a Turkish and an Israeli national, remain at large.
Tuesday's session was adjourned until Jan. 6 to give the prosecution more time to provide additional documents.