Belarusian opposition leader Alexander Milinkevich is calling on supporters to keep up their protest of President Alexander Lukashenko's landslide re-election.
He told activists in Minsk's October Square Tuesday to gather every day until a huge rally Saturday.
Several thousand were in the square as night fell Tuesday, defying an official ban on such gatherings. Five European ambassadors - including those from Britain, France, and Latvia - appeared at the rally.
Riot police have made no move to break up the crowd.
Election officials say President Lukashenko won a third term Sunday with 83 percent of the vote while Milinkevich won six percent.
U.S. and European Union officials have condemned the election as a fraud and are considering new sanctions against Belarus.
Russian monitors said the vote was free and transparent, while political observers say Mr. Lukashenko enjoys genuine support from elderly and rural Belarusians.
Earlier, police detained at least four opposition activists and several foreigners. Authorities sentenced the head of the United Civil Party, Anatoly Lebedko, to 15 days in jail for joining an unauthorized demonstration.
The United States has accused President Lukashenko of being Europe's last dictator because of his suppression of human rights and free speech.
Some information for this report was provided by AFP, AP and Reuters.