Observers from the European security organisation OSCE are questioning the outcome of Monday's presidential election in Belarus, saying the vote count was flawed.
And US President Barack Obama has strongly condemned the Belarus government for detaining thousands of protesters following a public outcry over the election result, which returned President Alexander Lukashenko to office for a fourth term.
The observers criticised both the counting of votes and a violent backlash against opposition candidates.
The most prominent of them, Vladimir Neklyaev, was reportedly badly beaten by police, then abducted from his hospital bed.
His wife Olga told the BBC he was taken away by men in civilian clothes who had "no ID on them".
The wife of another candidate, Alexi Michalevich, says her husband was abducted from their home.
At least seven presidential candidates were among those detained during protests in the capital, Minsk.
The BBC reports that Mr Lukashenko, who has been in power since 1994, has accused opposition supporters of "banditry", saying they'd turned into beasts.