Demonstrators took to the streets of Minsk in their tens of thousands on Sunday.
It marked the beginning of the fifth week of daily protests calling for Belarusian President Alexander Lukashenko's resignation in the wake of allegedly manipulated elections.
Unrest broke out in Belarus after authoritarian leader Lukashenko, who has ruled the former Soviet nation for 26 years, declared his own re-election with 80% of the vote on August 9.
The crowds brandished the historical white-red-white flag used before Belarus became a Soviet Republic, which has been taken on by the opposition in the country.
The slogan of this Sunday's march was "One for all and all for one", with protesters aiming to demonstrate that people are united in their desire for change.
As the rain fell down, they converged together from different districts of the Belarusian capital in the city centre, initially heading for Lukashenka's residence — the Independence Palace.
As in previous weeks, the palace and other official buildings were blocked off by authorities.
There was a massive military presence in Minsk that included army troops, tanks, water cannons, armoured personnel carriers and armoured reconnaissance vehicles.
At least 37 demonstrators had been arrested on the sidelines of the demonstration by the late afternoon, according to the Belarusian human rights group Viasna.
Metro stations in Minsk's centre were closed off.
Some political commentators on Twitter suggested these were the largest protests in Belarusian history.
“This sea of people cannot be stopped by military equipment, water cannons, propaganda and arrests. Most Belarusians want a peaceful change of power and we will not get tired of demanding this," said Maria Kolesnikova, a leader of the Coordination Council set up by the opposition to try to arrange a dialogue with the 66-year-old Lukashenko about a transition of power.
Protests were also reported on Sunday in Gomel, Belarus' second-largest city, as well as Brest and other regional capitals.
On Saturday thousands of women marched through the capital of Belarus, calling for the resignation of Alexander Lukashenko.
University students also demonstrated against the detention of classmates during the wave of protests that have gripped the country for the past four weeks.
For the first time in the demonstrations, supporters of LGBT rights appeared with rainbow flags in the women's march in Minsk, an indication that opponents of President Lukashenko are becoming bolder.
The main opposition challenger in Belarus’ disputed presidential election Sviatlana Tsikhanouskaya on Friday urged the international community to impose sanctions on “the individuals that committed electoral violations and crimes against humanity” and take other measures to stop the violence against protesters.
She told the UN Security Council that Lukashenko engaged in a “cynical and blatant attempt ... to steal the votes of the people” and “does not represent Belarus anymore.”
“A nation should not be a hostage to one man’s thirst for power, and it won’t,” she said. “Belarusians have woken up. The point of no return has passed.”