Serbian authorities on Monday cautiously welcomed the appointment of a U.S. prosecutor as head of a task force looking into claims that serving Kosovo leaders were involved in organ trafficking during a 1999 conflict with Serb forces.

The appointment of John Clint Williamson as head of the task force was made after a 2010 report accused Kosovo's Prime Minister Hashim Thaci of a number of crimes, including organ trafficking.

Thaci, a wartime rebel leader, denies the allegations.

Williamson is a former ambassador for war crimes issues in the US State Department.

"We would like to hope that the probe will be unprejudiced, despite the fact that there is a certain pessimism about the appointment of a man who, perhaps, the Serbian people do not trust," said Goran Bogdanovic, head of the Serbian government committee on Kosovo.

The report by special rapporteur Dick Marty alleged that organs were taken from prisoners killed by the Kosovo Liberation Army (KLA) during the 1999 war against Serb forces.