The draft report on the human rights situation in Kosovo, which was seen by the BBC, is the result of a two-year investigation by Council of Europe special rapporteur Dick Marty. The report is due to be published on Thursday.

The BBC said that the draft "confirms many of the details of a special BBC investigation in April 2009," which found that a special group within the KLA, known as the Drenica group, led by Thaci, had been involved in organised crime during the war, including drug trafficking and the trafficking of human organs.

Evidence is also presented of organised crime activities continuing up to the present day, the BBC said.

The Kosovo government has dismissed the draft as "baseless and defamatory" and threatened legal and political action against the "slanders".

"Allegations published by the media were investigated more than once by local and international law-enforcement institutions, and each time it was determined that they were baseless," the government said in a statement on Wednesday, as quoted by German news agency DPA. The government urged Council of Europe members to reject the report.

Serbian Foreign Minister Vuk Jeremic said while on a visit to Moscow that Thaci's future was uncertain after the publication of the report.

"I don't know what sort of future this person has, if you take into account the report about the investigation from the Council of Europe about his participation in the heroin trade, trafficking in people and human organs and his role as the head of one of the most organised criminal-mafia clans in the Balkans," Jeremic was quoted by Reuters news agency as saying.

Serbian deputy war crimes prosecutor Bruno Vekaric said that the report was a victory and justice for Serbia. "The report means a great victory of our country in its struggle for the truth and justice," Vekaric told the Belgrade newspaper Vecernje Novosti.

Vekaric said he expected the report to result in further investigations into trafficking in human organs in Kosovo and Albania whose judicial authorities had ignored for years calls to deal with that issue.

Vecernje Novosti said that the investigation was prompted by a book by former Hague tribunal chief prosecutor Carla del Ponte, in which she said that over 300 Serbs, Roma and disloyal Albanians had been kidnapped in Kosovo and transferred, after the 1999 NATO bombing campaign, to camps in northern Albania where their organs were removed.

Serbian war crimes prosecutors conducted a thorough investigation and sent several hundred pages to Marty, with whom they met in Switzerland last year. His assistants last year attempted to enter the infamous "yellow house" in northern Albania, but local residents would not let them, the newspaper said.