NATO was aware that current PM Hashim Thaci is ringleading major criminal networks in Kosovo at the time of NATO's operations in Serbia, shows an internal report leaked to the Guardian.

The report, produced by NATO's Kosovo force KFOR and dated 2004, states that Thaci is among three persons pinpointed as the "biggest fish" in the criminal organizations, the other being Xhavit Haliti, a former head of logistics for the Kosovo Liberation Army, who is said to have extensive criminal connections in the region.

During the 1998-9 turmoil that led to NATO's invasion of Serbia, Thaci was the leader of the KLA.

NATO forces intervened to quell what the international community believed to be ethic cleansing of ethnic Albanians from Kosovo.

In the ensuing events, NATO bombed various sites in Serbia, including civilian targets such as factories and the National Television, resulting in dozens of civilian deaths.

In February 2008, Kosovo declared independence from Serbia. Thaci was Kosovo's PM 2007-2010 and in December 2010 and January 2011 his Democratic Party won snap general elections.

The KFOR report states that the Thaci-Haliti network is engaged in "prostitution, weapons and drugs smuggling," and has amply used the methods of "assassinations, detentions, beatings and interrogations" to enforce its power.

The report further gives detailed information about the range, extent and nature of the criminal networks.

Kosovo's PM came into worldwide focus after end of 2010 a special report by the Council of Europe found that he is involved in a network organizing forceful organ harvesting in Kosovo.

CE rapporteur Dick Marty has already suggested that western governments were aware of the criminal activities underway in Kosovo.

Tuesday the Council of Europe is expected to discuss the report and formally demand an investigation into the case.