Belarussian riot police broke up a protest march today just hours after a rally at which a top opposition leader proclaimed the launch of a movement to "liberate" the country from President Alexander Lukashenko.
With the march dispersed just outside the city centre, police began hunting down opposition leaders.
Belarussian police officers run to positions during a protest.
Opposition leader Alexander Milinkevich, in a public challenge to Mr Lukashenko, told the rally that more and more people were losing their fear of the man who has run Belarus with a rod of iron for 12 years.
"I declare the creation of a Popular Movement for the Liberation of Belarus," said Mr Milinkevich, one of two opposition candidates defeated by Mr Lukashenko in a March 19th election that activists say was blatantly rigged.
But after the rally broke up several hundred protesters headed for a pre-trial detention centre at the urging of a second opposition leader, Alexander Kozulin.
It was to that centre that police took 300 demonstrators rounded up early on Friday morning, according to opposition figures.
Police in full riot gear, began beating their shields with truncheons, stopped the march, fired stun grenades and charged protesters. At least two people were injured and taken to hospital.
Opposition protesters said they saw riot police haul Mr Kozulin from a car and detain him. Mr Milinkevich was not immediately picked up, though his spokesman was detained.
In an initial comment, Mr Milinkevich accused Mr Kozulin, his fellow opposition candidate, of foolhardiness in leading protesters away in a march after the successful rally.
Asked whether he now expected blanket arrests, he said: "I do not want to be a prophet, but one may expect the worst".
Addressing the rally, Mr Milinkevich (58) a soft-spoken former lecturer, said the wave of protests against Mr Lukashenko since the election represented "only a first storming of the regime.
"We will keep on working, but we will not put off the next storming for another five years. We will fight above all else for fair and honest elections," he declared.
Mr Lukashenko has made no major public statements since describing his victory as the failure of a Western-backed revolution he said was being fomented. He is due to be inaugurated on March 31st.
Demonstrators are demanding a re-run of the poll, which returned to power for five years a president accused in the West of pursuing Soviet-style policies, closing down media and cracking down on rivals.
Events in Belarus have set Russia, which endorses his victory, at odds with the United States and western Europe.
The mood was buoyant and festive among protesters trooping to Yanka Kupala park for an unauthorised rally after riot police stopped them from massing on October Square, the site of a tent camp cleared by police yesterday.