The human rights group Vyasna accuses Lukashenko of deliberately trying to erase Belarusian identity and "Russifying" the former Soviet republic. Vyasna said five of its observers were among those detained by police. The political opposition typically attempts to rally on the country's independence anniversary.
Freedom Day celebration
The government agreed to a "Freedom Day" concert, and thousands turned out for it on Sunday. Yet despite the government banning any protest or march, many people carried the red and white flag of the 1918 republic, which has become an opposition symbol.
Political observers said Lukashenko allowed the holiday to be celebrated to avoid a repeat of last year's unrest and the prospect of a new reprimand from the European Union.
"This topic came up during Lukashenko's meeting with EU commissioners," said analyst Alexander Klaskovskiy. "Europe sent a signal that authorities should let people celebrate the 100th anniversary of the Belarusian People's Republic."
Lukashenko has been in power since 1994. He has strangled opposition activities and independent news media throughout his rule, although he stepped up the crackdown after his 2010 re-election, throwing dozens in jail.