(Updates with fresh quote, paragraph 10)
PRISTINA, Serbia, Oct 25 (Reuters) - The United States on Wednesday dismissed Serbian claims that a referendum this weekend on a new constitution could restore Belgrade's lost sovereignty over Kosovo.
Serbia has been rallying voters to back its new constitution as the best way to halt the secession of the country's southern province, where the ethnic Albanian majority expects to clinch independence around the turn of the year.
The draft, which replaces the defunct constitution of late strongman Slobodan Milosevic, declares the United Nations-run territory of Kosovo an integral part of Serbia.
"What happens to you is a Kosovar matter, and an international matter," Ambassador Frank Wisner, Washington's Kosovo envoy, told reporters in the capital Pristina.
"It is not a matter of Serbian sovereignty, which changed when the U.N. agreed on 1244," he said.
U.N. Security Council Resolution 1244 was adopted in June 1999 after 78 days of NATO bombing drove out Serb forces accused of atrocities and ethnic cleansing in a two-year war with Kosovo Albanian guerrillas. Ten thousand Albanians died.
The resolution placed Kosovo under U.N. stewardship, and reserved a decision on its future for the Security Council.
Seven years later, U.N. mediator Martti Ahtisaari is due to make his recommendation by the end of 2006. Diplomats predict a form of independence under European Union supervision, amputating land many Serbs consider their religious heartland.
Wisner's language appeared to reflect consensus in the West that returning Kosovo to Serb control is no longer feasible.
"In the end it will be in the interests of both nations to have a strong bilateral relationship," he said later after meeting Kosovo's Prime Minister Agim Ceku. "We are going to pursue independence by the -- sorry -- we are going to pursue final status by the end of the year."
The U.S diplomat said he counted on Albanians, who make up 90 percent of Kosovo's 2 million people, to allow Serbs in the province to vote in the referendum on Saturday and Sunday.
Around 100,000 Serbs remain in Kosovo, many in enclaves guarded by troops of the 16,000-strong NATO-led peace force.
The proposed constitution, the fruit of rare consensus between government and opposition in Serbia, is expected to pass the referendum, and trigger early elections in December.
The U.S. and EU have indicated that elections in December could delay a decision on Kosovo into 2007, for fear of driving voters into the arms of ultranationalists.