The new United Nations administrator for Kosovo has appointed a special international prosecutor to lead an investigation into Wednesday's gun attack in which two youths from the Serb community were killed.
The situation in the region remains tense
At his first news conference in Pristina, Harri Holkeri described the attack as an act of inter-ethnic barbarism which was blighting the future of the province.
Unknown attackers sprayed the youths with machine-gun fire as they were swimming in a river near the Serb-inhabited enclave of Gorazdevac.
Mr Holkeri's comments came as hundreds of Serbs protested in northern Kosovo, and Serbia announced a day of mourning.
One of the dead is reported to have been 12 years old.
A big police search is under way in Kosovo following the murders.
The Serbian Deputy Prime Minister, Nebojsa Covic, called for an urgent session of the United Nations Security Council to stop what he described as "a wave of violence by the ethnic Albanian extremists".
"Kosovo is descending into a catastrophe," he said, calling the attack "a continuation of ethnic cleansing of Serbs from Kosovo".
In words that some have interpreted as raising the possibility of sending Serbian security forces back into Kosovo, he stressed that Serbs must defend themselves.
Concerns about violence
The Serbia and Montenegro news agency Tanjug said the situation in the village remained tense, with Serbs saying they no longer trusted the international community and increasing numbers saying they would leave the province.
UN officials said local Serbs blocked a key road in the village of Osojane in western Kosovo.
Holkeri (left) is expected to push ahead with direct talks
There were also reports that unknown suspects had thrown a grenade at the house of an ethnic Albanian in the divided northern town of Mitrovica.
There are concerns about an upsurge in violence in the province ahead of proposed talks between ethnic Albanian officials and the Serbian authorities.
The talks, which Mr Holkeri is expected to push ahead with, are expected to focus on common concerns while steering clear of the subject of the province's legal status.
The dialogue would be the first since the end of the 1999 conflict.
The Serbian Government has said it is prepared to grant autonomy to Kosovo but not full independence as demanded by ethnic Albanians.