Two leading members of a newly formed opposition council in Belarus were questioned on Friday in a criminal case over what President Alexander Lukashenko calls an attempt to seize power, after nearly two weeks of mass rallies against his 26-year rule.

More public figures, including an Olympic athlete, came out in opposition to Lukashenko, whose political challengers say he rigged an Aug 9 election.

In the latest act of protest, the streets of the capital Minsk were paralysed...