Unidentified masked men have detained a leading opposition figure in Belarus, according to local media, writes BBC.

Witnesses reportedly saw Maria Kolesnikova being bundled into a minibus in Minsk and driven away.

She was one of three women who joined forces ahead of August"s presidential election to challenge incumbent Alexander Lukashenko.

Mass unrest has followed his re-election amid allegations of vote-rigging.

The interior ministry said it detained 633 people on Sunday after a fourth consecutive weekend of protests. At least four people have died and hundreds have been injured as authorities have tried to crush dissent in the country.