Scattered groups of protesters in Belarus on Thursday sought to breathe life into a movement against President Alexander Lukashenko that fizzled out in the face of a severe crackdown.
The authorities responded by moving military vehicles into the centre of the capital Minsk, according to videos circulating on social media and published by local media, and by detaining activists, rights groups said.
Rallies erupted in the ex-Soviet country last August after Lukashenko claimed a sixth term in a vote the opposition and Western diplomats said was rigged.
But a sustained police crackdown saw weekly mass demonstrations in city centres peter out by the end of the year, with thousands of protesters detained and several killed.
The opposition has since changed tactics, calling for supporters to gather in small groups in every district.
The Nexta Telegram channel, which has mobilised and coordinated demonstrations, urged protesters to march through courtyards and organise flash mobs on Thursday.
Images published by local media showed small groups marching through Minsk waving red-and-white flags -- a symbol of the Belarus opposition -- and official red-and-green flags draped over state buildings.
The Viasna human rights group said that as of Thursday evening, police had detained more than 100 activists nationwide.
Following Nexta's call, drivers across the country sounded their horns and activists set off fireworks into the night sky.
"We want to declare March 25 the day when the cities are ours!" Nexta said.
- 'Belarus we deserve' -
The resumption of the protests coincides with Freedom Day in Belarus, which the opposition marks each year on the anniversary of a declaration of independence in 1918.
Officials have said the planned protests are illegal and moved to crack down on dissent this week, accusing a group representing Polish people in Belarus of stirring up racial hatred and the "rehabilitation of Nazism".
On Wednesday, the head of the Union of Poles in Belarus, Anzhelika Boris, was arrested and sentenced to 15 days in prison.
Police on Thursday searched the group's offices, the homes of its activists and at least one Polish school, detaining board member Andrzej Poczobut.
EU foreign policy chief Josep Borrell called Thursday on Minsk to release the group's members "along with all political prisoners currently detained".
Belarus's relations with Poland deteriorated after the EU member sheltered activists -- including the coordinators of Nexta -- who fled across the border to escape the crackdown.
Other critics, including opposition leader Svetlana Tikhanovskaya, found shelter in Lithuania after the August vote.
She has since lobbied Western governments to support her call for new elections in a country ruled by Lukashenko since 1994.
"I wish for all of us to meet next March 25 in the Belarus we deserve -- in a country where the law is respected, rights are respected and the people are respected," Tikhanovskaya wrote on her Telegram channel on Thursday.
Western governments have slapped sanctions on Lukashenko and his allies and say political novice Tikhanovskaya, 38, was the true winner of the vote.
- 'Second wave' -
EU Baltic states Lithuania, Latvia and Estonia on Thursday expanded sanctions against Belarus by imposing travel bans on more than 100 officials.
"The regime's supporters must realise that the response to the brutal use of force against peaceful citizens will be very strict and clear," Lithuanian Foreign Minister Gabrielius Landsbergis said in a statement.
Lukashenko, backed by Russian President Vladimir Putin, has claimed to have overcome an uprising directed by the West.
More than 400 people have been given lengthy jail terms over the protests.
The crackdown has instilled fear even in those "very keen on changes", said Alexander Klaskovsky, a Belarusian political scientist.
Nexta has also called for mass protests on Saturday, casting it as "the day we start the second wave of street protests".