Kosovo war veterans said Thursday an "unknown person" had handed them a new batch of confidential files about witnesses from a war crimes court in The Hague, in a potential major security breach.
The veterans, from the ethnic Albanian rebel group that waged a 1990s uprising against Serbia, are the target of the Hague-based Kosovo Specialist Chambers (KSC) investigating alleged war crimes.
The court's work is highly sensitive in Kosovo, where former rebel commanders are still at the apex of political life. Previous high-profile investigations have been hampered by witness intimidation.
The vice chairman of the veteran's club, Nasim Haradinaj, told media his association "received documents from an unknown person" on Wednesday who said "he would bring more".
The files allegedly include details on protected witnesses in Serbia, the club said.
Last Monday, the organisation said a person "wearing glasses, a mask and a hat" left them a package of 4,000 documents revealing information about identities of protected witnesses.
Hague investigators promptly arrived to seize both files, the veterans said, though the court has refused to comment on the matter or confirm the authenticity of the documents.
"We had an awkward visit", the chairman of the veteran's group, Husni Gucati, said Thursday.
"Special court investigators came. They accept that it is their documents, the special court files."
The tribunal operates under Kosovo law but is based in the Netherlands to shield witnesses from threats at home.
Kosovo veterans fiercely oppose the work of the court, defending their "just" liberation war against Belgrade's oppression of Kosovo's ethnic Albanian population.
President Hashim Thaci -- the rebels' former political chief -- was the first to face accusations from the court's prosecutors earlier this year.
He was accused of being "criminally responsible for nearly 100 murders" in addition to other crimes against Serb, Roma and Kosovo Albanian victims.
Prosecutors said they took the unusual decision to publish his indictment before it was confirmed by a pre-trial judge because he was trying to "obstruct the work" of the tribunal.
The conflict claimed 13,000 lives, mainly Kosovo Albanians. Top Serbian military and police officials have already been convicted of war crimes under international justice.