Three ethnic Albanians from Kosovo have entered pleas of not guilty to charges of war crimes and crimes against humanity at the international war crimes tribunal.
The four suspects were members of the Kosovo Liberation Army
The men, Haradin Balaj, Isak Musliu and Agim Murtezi, were arrested on Monday and are the first Albanians to be charged by the tribunal.
They are all former members of the disbanded guerrilla group the Kosovo Liberation Army (KLA).
Together with a fourth man, Fatmir Limaj, who is currently under arrest in Slovenia, they are accused of torturing and killing Serb and Albanian prisoners in the late 1990s.
Finally, the latest actions by K-For and the UN security bodies give us hope that justice is not blind after all and that it is not one-sided, as it seemed for years
Serb National Council of Kosovo
Mr Limaj is being held in Slovenia, waiting to be transferred to The Hague.
The four are accused of routinely beating and torturing 35 Serbian or Albanian inmates at the KLA's Lapusnik Prison.
In addition, when the camp was overrun in July 1998, they allegedly took some of the inmates to the mountains where Mr Balaj and Mr Murtezi are accused of shooting 11 of them dead. The fate of two others is unknown.
The tribunal said in a statement on Wednesday that Mr Limaj was arrested on Tuesday afternoon in Kranjska Gora, near the border with Italy and Austria.
Limaj is in custody in Slovenia
He will be extradited to The Hague when the Slovenian authorities receive the tribunal's indictment against him.
Mr Limaj flew out of Kosovo on a business trip on Friday despite an arrest warrant issued against him and the three others three weeks ago.
The chief prosecutor at the war crimes tribunal, Carla del Ponte, criticised the international peacekeeping force, K-For, for allowing Mr Limaj to avoid arrest.
The Hague tribunal has been accused in the past of turning a blind eye to war crimes committed by ethnic Albanians in Kosovo during their 1998-99 conflict with Belgrade.
Representatives of the minority Serb community in Kosovo welcomed the arrests.
"The Serb people have been resignedly awaiting justice for three years now," said a statement by the Serbian National Council of Kosovo-Metohija, quoted by the Serbian news agency FoNet.
"Finally, the latest actions by K-For and the UN security bodies give us hope that justice is not blind after all and that it is not one-sided, as it seemed for years."