Top Belarussian opposition leader Alexander Milinkevich has been sentenced to 15 days in jail shortly after his arrest in the capital Minsk. Wednesday, he was warned not to attend a rally marking the 20th anniversary of the Chernobyl nuclear disaster.
Alexander Milinkevich was sentenced to jail for the crime of "taking part in an unsanctioned march" late on Wednesday.
It is the same sentence passed on scores of opposition supporters who held unprecedented street protests after the controversial election of longtime leader Alexander Lukashenko last month.
But until now the country's top opposition leader had avoided arrest.
Prosecutors warned Milinkevich not to take part in Wednesday's rally, which had been approved, but police say the march to the rally site was unsanctioned.
Milinkevich's campaign manager and the leaders of other opposition parties were arrested just after the demonstration in downtown Minsk.
The crowd of around 10,000 people gathered to commemorate the 20th anniversary of the Chernobyl nuclear accident.
An explosion and fire at the nuclear plant spread radioactive fallout over one-fourth of Belarussian territory, and has had a lasting impact in Belarus, Russia and Ukraine, where the nuclear plant is located.
An event to mark the anniversary is held each year, but the rally Wednesday took on a new edge in the wake of the election.
Various speakers denounced the government's response to the Chernobyl disaster, especially the policy of resettling people in the contaminated zone.
Mr. Lukashenko maintains the dangers of radiation have been exaggerated, despite a high number of cancers and other ailments among those who live close to the now-closed nuclear plant.
After his arrest, Milinkevich vowed that the opposition would push ahead with their campaign.
By official count, Milinkevich trailed far behind Mr. Lukashenko, who has ruled Belarus with a strong hand since 1994.
Often referred to as "Europe's last dictator", the Belarussian leader had to change the constitution in a controversial referendum two years ago in order to run for a new term.
European observers said the election was not free or fair, and Milinkevich led a week of unprecedented protest rallies after the vote.
The protests ended after police broke up a rally and arrested another top opposition leader, who remains in jail.
The European Union and the United States later applied sanctions against the regime, including a visa ban on most top officials including Mr. Lukashenko.
Russia continues to back the Belarussian leader..