BRUSSELS, Belgium -- A special European Union prosecutor said Tuesday he had "compelling indications" that up to ten captives were killed to have their organs harvested for illegal trafficking and black market sale during the 1998-99 Kosovo war.

The revelation was part of a presentation on a 2 1/2 year investigation into atrocities that also largely confirmed human right reports that there was a campaign of persecution of Serb, Roma and other minorities by some people in the rebel Kosovo Liberation Army.

Clint Williamson, the chief prosecutor, said the Special Investigative Task Force would in future be "in a position to file an indictment against certain senior officials of the former Kosovo Liberation Army" for a series of crimes, including killings, disappearances, camp detentions and sexual violence.

The killing for organ harvesting has long been a key aspect of the probe. Williamson said that the level of evidence was not yet sufficient to prosecute the alleged crimes.

The EU probe followed a 2011 Council of Europe report alleging that the rebel KLA ran detention camps on Albania's border during Kosovo's war for independence from Serbia. It alleged that civilian captives were killed there and their organs sold as part of an illegal trade linked to senior KLA commanders.

Without naming any individuals, Williamson said that "there are compelling indications that this practice did occur." He went to lengths to make clear the alleged harvesting was not a wholesale practice, rejecting claims of hundreds of victims. Some 400 people -- mostly Kosovo Serbs -- disappeared near the end of the war.

"Handful was meant literally -- 10," Williamson said, holding up two hands with outstretched fingers. "That is the approximate range of the number."

"The fact that it occurred on a limited scale does not diminish the savagery of such a crime," he said.

About 10,000 people died in Kosovo's 1998-99 war for independence before NATO intervened to force Serbia to end its brutal crackdown against Kosovo separatists and pull its troops out of the territory.

Serbia has vowed never to recognize the independence of its former province, which many Serbians consider their nation's heartland.

In Belgrade, Serbia's war crimes prosecutor Vladimir Vukcevic told The Associated Press that Tuesday's announcement "crowns a big effort on our part and shows that we were right when we said that war crimes had been committed and that organ trafficking took place."

In Kosovo, Ardian Arifaj, an adviser to Prime Minister Hashim Thaci, said the country hoped for more clarity at the end of Williamson's investigation, but added the authorities will continue to work with international officials to conclude the issue.

Thaci was also a former KLA leader and Williamson bitterly complained that the investigation had been made far more difficult because of "a climate of intimidation that seeks to undermine any investigations of individuals associated with the former Kosovo Liberation Army."

AP writers Jovana Gec contributed from Belgrade, Serbia, Nebi Qena from Pristina, Kosovo and Mike Corder from The Hague, Netherlands