Tens of thousands of people in Belarus have flooded into the streets demanding the resignation of the country's authoritarian leader Alexander Lukashenko, who on the same day marked his 66th birthday.
Security forces were present in large numbers in the capital Minsk, where the main Independence Square had been cordoned off with metal barriers.
But that did not stop the demonstrators from trying to move in, leading to confrontations with police. Some officers repeatedly attacked peaceful demonstrators, according to a dpa reporter at the scene.
Other uniformed men tried to push back the people with off-road vehicles that had high metal grilles attached on the front bumper.
Pictures showed women lying down in front of them in the street.
Videos and images from the rally also showed uniformed men leading away mainly male protesters. There were screams and protesters shouted "Shame!" at the police.
The Interior Ministry said more than 150 people had been arrested by the afternoon.
Earlier, officials had warned that the demonstration had not been authorised and threatened violence.
The pro-democracy movement ignored the threats and said that as Mr Lukashenko celebrated his 66th birthday, he should see that the people were against him after ruling for 26 years.
The motto of the protest march was "For Peace and Independence."
On the last two Sundays, hundreds of thousands took to the streets of Belarus to protest "Europe's last dictator," as they dub Mr Lukashenko.
In the past few days, other demonstrations were disbanded and people arrested, indicating the power apparatus might not permit a fresh mass demonstration.
Russian President Vladimir Putin also expressly promised Mr Lukashenko support from his country's security forces in what is seen as a ploy to intimidate the protest movement in the ex-Soviet republic.
A face-to-face meeting between Mr Lukashenko and Mr Putin is planned in Moscow in the coming weeks, the Kremlin announced on Sunday.
