Fatmir Limaj, Isak Musli, and Hardinaj Bala, former commanders of a Kosovo Liberation Army-operated detention camp, are due to go on trial on November 15. They are charged with unlawful detention, torture and killing of Serb civilians and Albanian collaborationists in June 1998.
In an attempt to protect witnesses, the Hague tribunal last week decided the indictees could communicate only with their counsel and families.
The chief prosecutor in the case, Andrew Caley, told today's status conference witnesses in Kosovo were being intimidated and harassed as part of an organised and systematic campaign.
He informed defence counsel about five instances in which representatives for the defence contacted prosecution witnesses without permission. He added the prosecution would present evidence at the trial to prove the allegations of witness intimidation.
Defence counsel Gregor Guy-Smith and Karim Khan dismissed the allegations, demanding concrete evidence.