Al Jazeera’s Step Vaessen, reporting from Minsk, said the capital was “a city filled with anger and frustration” and described “hectic scenes” that “Minsk hasn’t witnessed before”.
“They’re very defiant but also very scared because riot police are out in force. They are detaining people right in front of us so people are spreading around trying to get away from police,” Vaessen said.
Lukashenko, 65, a former Soviet collective farm boss, faced unprecedented protests against his rule before the vote, after opposition groups united behind Tsikhanouskaya, a 37-year-old former teacher, when other contenders were either jailed or kept off the ballot.
The stay-at-home mother, who ran after her husband Sergei, a political blogger, was detained and barred from the race, drew huge crowds at rallies nationwide.
For the opposition, “the main thing is to accept defeat”, Central Election Commission Chairwoman Lidia Yermoshina said of the preliminary results on state TV.
Turnout was 84 per cent, the Tass news service reported, citing the commission, which is due to publish official results on Monday.
Tsikhanouskaya told reporters at a news conference after the exit poll that she did not recognise the results and that the majority was with the opposition, Radio Free Europe reported on its website.
The result compares to 83% won by Lukashenko in 2015 elections. Opposition activists have complained that high levels of early voting recorded ahead of polling day was an indicator of ballot fraud.
The European Platform for Democratic Elections reported that observers had been restricted and detained during early voting.
Three other candidates were also on the ballot in the nation of 9.4 million, located between Russia and the NATO states of Poland, Lithuania and Latvia.