Europe's top human rights watchdog is looking into Serbian allegations of organ trafficking by Albanian guerrillas.
Dick Marty, a Swiss senator representing the Council of Europe, is leading the probe.
The Serbs accuse ethnic Albanian guerrillas of kidnapping Serb civilians during Kosovo's war, removing their organs and selling the body parts on the black market.
Marty is expected to meet top Serbian judiciary and war crimes officials during his two-day visit to Belgrade starting on Monday.
Serbian officials say up to 500 Kosovo Serbs vanished without a trace during the 1998-99 war. They claim at least some of them may have had organs removed.
Ethnic Albanian officials deny the claims. They say the allegations are part of Serbian propaganda against Kosovo's independence, declared last year with Western backing.
The allegations were first made public in a memoir last year by Switzerland's Carla Del Ponte, the former chief United Nations war crimes prosecutor. In "Madame Prosecutor", an account of her tenure as head of the International Criminal Tribunal for former Yugoslavia, Del Ponte said her office had been tipped off to possible organ trafficking.
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