UNITED NATIONS — As “excited” but “tense” Kosovo is preparing to declare independence as early as this weekend, Serbia and Russia are asking to convene the Security Council for an emergency session today in a last-ditch effort to reverse the American- and European-backed plan to end Belgrade’s sovereignty over the majority-Muslim province.

While Serbia’s foreign minister, Vuk Jeremiç, and Russian diplomats are expected to register their protest during the closed-door session today, most diplomats here doubt the council could change any realities on the ground, where a transition to independence in Kosovo is closely coordinated with Washington and key European capitals. The declaration is expected before, or immediately after, the European Union meets Monday to authorize a new force that will assume security responsibilities over Kosovo.

Belgrade will take retaliatory measures against countries that will recognize a “fake state” in Kosovo, Prime Minister Kostunica of Serbia said. He had not called on Kosovo’s Serbian population to take arms, but even localized flareups in the Balkans have led to major European violence several times in the last century, and the fast-moving birth of a new country there this weekend may have unpredictable consequences.

“The people of Kosovo have been waiting for such a long time, there is tremendous excitement,” an international relations professor at the New School, Anna DiLellio, said. Ms. DiLellio, who has spent years in Kosovo in several advisory capacities, said the ethnic Albanian population has long held up any political disagreements while the Pristina leadership is slowly moving toward independence.

“A friend of mine told me yesterday that the best thing about independence is that now she can finally protest against the government,” Ms. DiLellio said. But, she said, the excitement and anticipation are mixed with concern about possible violence, especially Orthodox church-led localized flareups in the northern part of the province, where there is a large Serbian ethnic population. NATO forces are reportedly being beefed up in sensitive areas.

“People here are tense,” a Pristina-based senior U.N. official said, speaking over the telephone yesterday on condition of anonymity. “Rumors are circulating that populations will start to be moved around,” she said, referring to ethnic exchanges between Serbians and Albanians. But, she added, “We have no substantiation of that. The Albanian leadership has promised a pluralistic state.”

The United Nations has effectively governed Kosovo since 1999, after the NATO-led air assault against Serbia. A U.N. envoy, Martti Ahtisaari, has recently devised a plan for a supervised transition toward Kosovo’s independence, but it was rejected by Belgrade and Moscow. America and the European Union, arguing the current situation is unsustainable, orchestrated a move toward independence despite Belgrade’s steadfast opposition.

A senior European diplomat who briefed U.N. reporters on condition of anonymity yesterday said that soon after the declaration of independence, he expected the European Union to provide its members with the opportunity to bless the new country, and that most will “move quickly to recognize Kosovo.” Washington also will quickly recognize the new state, but Russia is expected to block a U.N. membership for Kosovo, and many countries, including some that are concerned about breakaway provinces of their own, may snub Pristina’s declaration as well.