|The report comes days after an election in Kosovo in which Thaci came ahead [Reuters]
Hashim Thaci, Kosovo's prime minister, headed up a "mafia like" crime ring responsible for smuggling weapons, drugs and human organs, a Council of Europe report alleges.
The draft report, which follows a two-year investigation, says civilians detained by the Kosovo Liberation Army (KLA) were shot dead in northern Albania for their kidneys, which were then sold on the black market.
The Kosovo government on Wednesday denounced the report, which does not name its sources or give the number of victims, as baseless and slanderous, threatening legal and political action.
Its release comes as Thaci, a former key leader in the KLA, tries to form a coalition government after claiming victory in last week's election.
The draft, written by Dick Marty, Swiss Council of Europe deputy, said there was substantial evidence that Serbians and some Albanian Kosovars had been secretly imprisoned by the KLA in northern Albania during the 1998-99 conflict "and were subjected to inhuman and degrading treatment, before ultimately disappearing".
It said in the wake of the Kosovo war, before international forces had time to re-establish law and order there, "organs were removed from some prisoners at a clinic in Albanian territory, near Fushe-Kruje...".
Hashim Thaci headed a "small but inestimably powerful group of KLA personalities" called the Denica group that "wrested control of most of the illicit criminal enterprises ... beginning at the latest in 1998," Marty wrote.
"Thaci and these other 'Drenica Group' members are consistently named as 'key players' in intelligence reports on Kosovo's mafia-like structures of organised crime."
He said that Thaci owed his position to "having secured political and diplomatic endorsement from the United States and other Western powers, as the preferred domestic partner in their foreign policy project in Kosovo".
"This form of political support bestowed upon Thaci, not least in his own mind, a sense of being 'untouchable' and an unparalleled viability as Kosovo's post-war leader-in-waiting.
His report concludes that during and just after the war, Thaci and fellow members of his Kosovo Liberation Army carried out "assassinations, detentions, beatings and interrogations".
The European Union police and justice mission (EULEX) in Kosovo said it would examine the allegations.
"We'll be looking at the report carefully," Andy Sparkes,the deputy head of EULEX, told the Reuters news agency.
"If they have got chapter and verse on this kind of thing, then obviously we would like to hear from them more formally so that we can deal with it."
Vladimir Radomirovic, editor of the Serbian whistleblowing site, The Whistle, told Al Jazeera that the report tallied with previous claims made by the Serbian government.
"Every single Serbian government from 1998 to today has claimed that Hashim Thaci was the leader of an organised crime gang leading up to the Kosovo, during the Kosovo war and afterwards.
"Now the Serbs feel vindicated because all these allegations have been confirmed by the Council of Europe," he said.
"It is Belgrade's argument that Hashim was behind all this - maybe not himself killing people - but that he organised the crime group that smuggled drugs and traded in human organs."
But he added they had not seen any "concrete evidence" from the prosecutor's office of the claims.
Serbia's foreign minister said the report was "a signal showing that it is time for the civilised world community to stop turning their backs to the terrible situation of Kosovo," adding that it threw Thaci's future into doubt.
"I don't know what sort of future this person has ... this report shows what Kosovo is and who is heading it," Vuk Jeremic said.
However, Jakup Krasniqi, Kosovo's interim president, dismissed the report as "full of clear fabrications, non-existent facts and allegations which are not confirmed by international justice".
"Attempts to mix up the victims with the executioner cast a shadow of suspicion on all the activity and impartiality of the Council of Europe's rapporteur," he said.
Thaci became a key leader in the KLA, which sought to separate Kosovo from Serbia. His role in the paramilitary group was partly to train Albanian recruits and dispatch them to Kosovo to fight.
At the end of the conflict in 1999, the KLA disbanded. A number of its leaders formed the Democratic Party of Kosovo, including Thaci who is now its leader.
The claims against Thaci first arose in the memoirs published in 2008 of former UN chief war crimes prosecutor Carla Del Ponte, which prompted the Council of Europe to reopen the case briefly investigated by her office five years ago.