One of Belarus's leading opposition figures Maria Kolesnikova has been detained while trying to cross into Ukraine, Belarusian border officials said Tuesday.
Kolesnikova was detained while attempting to cross overnight with two other members of the opposition's Coordination Council who were able to pass through to Ukraine, Anton Bychkovsky, a spokesman for the State Border Committee, told AFP.
She and the two other council members, press secretary Anton Rodnenkov and executive secretary Ivan Kravtsov, had disappeared on Monday.
Bychkovsky said Rodnenkov and Kravtsov were able to cross into Ukraine, and the Ukrainian embassy in Minsk confirmed to AFP they were in the country.
Kolesnikova was being held and "an investigation is under way to legally assess the situation," Bychkovsky said.
State news agency Belta quoted border officials as saying the three had tried to cross the border in a BMW car around 4:00 am Tuesday.
The Coordination Council was set up to ensure a peaceful transfer of power after President Alexander Lukashenko's main rival Svetlana Tikhanovskaya rejected his claim to have won an August 9 presidential election with 80 percent of the vote.
The disputed election has sparked widespread protests and a harsh police crackdown.
Germany and Britain had on Monday demanded answers after Kolesnikova went missing and allies said she had been snatched off the streets.
Kolesnikova, 38, is the only one of the trio of women who fronted Tikhanovskaya's campaign to remain in Belarus.
Tikhanovskaya left the country under pressure from the authorities and was granted refuge in EU member state Lithuania, while her other campaign partner, Veronika Tsepkalo, is now in Ukraine.
Police in Belarus have been intensifying efforts to crack down on the opposition, with more than 600 people arrested on Sunday during the latest in a series of huge weekend protests against Lukashenko.
The European Union has refused to recognize the results of the vote and warned of sanctions against those involved in the election and violence against protesters.
Thousands of protesters were detained in the days after the vote with many detainees accusing police of beatings and torture.
EU diplomatic chief Josep Borrell on Monday said the bloc expected "Belarusian authorities to ensure the immediate release of all detained on political grounds before and after the falsified 9 August presidential elections."
Kolesnikova's office said witnesses described her being snatched off the street in the capital Minsk on Monday morning by unidentified men in black who bundled her into a minibus marked "Communications".
Belarusian authorities had already detained several members of the Coordination Council and others have left the country under official pressure. One, Olga Kovalkova, said on Saturday she was in Poland after security services threatened her and took her to the border.
Kolesnikova and other members including Nobel Literature Prize winner Svetlana Alexievich have faced questioning in a probe over an alleged bid to seize power.
Kolesnikova, a trained flautist and music teacher, entered politics to run the campaign of another opposition politician, ex-banker Viktor Babaryko, who attempted to stand for president against Lukashenko but was jailed and barred from running.