PARIS – Civilians detained by the Kosovo Liberation Army were allegedly shot to death in northern Albania so their kidneys could be extracted and sold on the black market after the war in Kosovo ended in 1999, according to a report prepared for Europe's premier human rights watchdog.

The report by Council of Europe investigator Dick Marty — more than two years in the making — also suggested Kosovo's U.S.-backed prime minister was once the "boss" of a criminal underworld behind the alleged grisly trade.

Kosovo's government branded the report as "baseless" and described it as an attempt "to tarnish the image of the Kosovo Liberation Army." In a statement, the government also accused Marty of bias and "fabrications."...