Police in Minsk have broken up an unapproved rally by several thousand people marking 90 years since Belarus's first declaration of independence.
Protesters chanted "Long Live Belarus" at the rally
Dozens were arrested at the rally, an event which in recent years has become a protest against the authoritarian rule of President Alexander Lukashenko.
Riot police beat protesters as they broke up the rally, witnesses say.
Mr Lukashenko has been branded Europe's "last dictator" by the US but he remains broadly popular in Belarus.
Protesters waved European Union flags and chanted "Long Live Belarus" as police ordered them to disperse.
Witnesses said after about an hour police waded in and forcibly dragged protesters onto waiting buses.
Human rights activists said more than 100 people were taken into custody.
Opposition leader Anatoly Lebedko told the Associated Press news agency that the authorities had shown there was "no freedom of speech nor freedom to gather" in Belarus.
The US has criticised President Lukashenko's authoritarian regime
Interior Minister Vladimir Naumov had said before the rally that additional forces would be deployed and that "any unsanctioned march will be prevented in accordance with the necessary laws".
The BBC's Gabriel Gatehouse in neighbouring Ukraine says the anniversary of the 1918 declaration has in recent years become a rallying point for opposition to the government.
The independent Belarusian People's Republic was short lived - it fell to the Bolsheviks within months.
The Belarus leadership has criticised the anniversary for being anti-Soviet.
Allegations of vote-rigging during his re-election as president in 2006 led to Mr Lukashenko and a number of his top officials being banned from travelling to the US or the European Union.
He officially won 83% of the vote with his nearest opposition rival, Alexander Milinkevich, taking 6%.
Analysts note that many Belarussians credit Mr Lukashenko with maintaining economic stability and paying pensions on time, and for avoiding the post-communist turmoil seen in neighbouring countries.