Thousands of Belarusians have again defied authorities to rally against President Alexander Lukashenko's re-election in a vote the West has condemned as a fraud.
Backers of chief opposition leader Alexander Milinkevich say they will hold a round-the-clock protest in central Minsk.
Milinkevich calls the election a farce and is demanding a free and fair democratic vote.
Belaruisian election officials say Mr. Lukashenko won 83 percent of the votes Sunday while Milikenvich won six percent.
European election monitors say the vote was marred by intimidation and widespread arrests of opposition supporters. European Union External Affairs Commissioner Benita Ferrero-Waldner says new sanctions are "very likely."
A U.S. State Department spokesman Sean McCormack called election conditions in Belarus "appalling."
He says Washington is preparing to take serious measures against those responsible for fraud and human rights abuses. But Russian election observers say the voting was fair and transparent.
President Vladimir Putin has congratulated Mr. Lukashenko on winning a third term.
Mr. Lukashenko has wide support among many elderly and rural Belarusians who believe he has kept the country stable after the collapse of the Soviet Union.
But the United States calls him Europe's last dictator because of his suppression of human rights and free speech.
Information for this report is provided by AFP, AP and REUTERS.