The president of the U.N. war crimes tribunal branded Yugoslavia a "rogue state" Thursday, saying its government has refused to allow an investigation of alleged atrocities in Kosovo.

Authorities in Yugoslavia confirmed they had denied visas to tribunal prosecutor Louise Arbour and 11 members of her staff.Gabrielle Kirk McDonald, the tribunal's U.S. president, said Yugoslavia had once again shown "utter disregard for the norms of the international community."

"Essentially, it has become a rogue state, one that holds the international rule of law in contempt," she said.

Arbour would not say what her next step would be. She said her visa request was a matter of courtesy and that she has a legal right to carry out investigations in Kosovo.

Although wars in the former Yugoslav republics prompted the U.N. Security Council to create the tribunal, the tribunal argues its jurisdiction also extends to what remains of Yugoslavia. Kosovo is in Serbia, the largest of Yugoslavia's two remaining republics.

Hundreds of people have been killed and hundreds of thousands left homeless in seven months of fighting between Serb forces and secessionist ethnic Albanian rebels in Kosovo. U.N. investigators want to check reports of atrocities on both sides.

Kirk McDonald, a judge from Texas, said she would report the matter to the Security Council, whose authority, she said, had been challenged. Meanwhile, she canceled a visit to the Yugoslav capital, Belgrade, to speak to a conference on war crimes trials.

"This move by the Yugoslav government will have serious legal consequences," said Natasa Kandic, chief of the Humanitarian Law Center organizing the conference.

"With it, the Yugoslav government acted directly contrary to the U.N. Security Council resolution demanding free access to international investigators to Kosovo."