In this file photo taken on August 24, 2020 Lawyer Maxim Znak, a member of the Coordination Council formed by the opposition to oversee efforts for a peaceful transition of power, attends a press conference on the 16th day of protests over disputed presidential elections results in Minsk. (SERGEI GAPON / AFP)

Belarusian opposition politician Maxim Znak was detained on Wednesday by masked men wearing plain clothes, supporters said, as authorities extended a systematic campaign to round up the leaders of a month-long mass protest movement.

Znak was detained two days after another opposition leader, Maria Kolesnikova, was snatched in the street by masked men. Both are prominent leaders of protests demanding the resignation of President Alexander Lukashenko following an Aug. 9 election that the opposition says was rigged.

Znak was the last member of the opposition’s Coordination Council still active inside Belarus apart from Nobel prize-winning author Svetlana Alexievich, who has served as a figurehead for the movement

Znak was the last member of the opposition’s Coordination Council still active inside Belarus apart from Nobel prize-winning author Svetlana Alexievich, who has served as a figurehead for the movement.

All the rest have fled, been forced abroad or been detained in a crackdown by Lukashenko’s security forces as he seeks to maintain his 26-year grip on power in the former Soviet republic.

READ MORE: Kremlin: Belarus' Lukashenko to visit Moscow 'in coming days'

Znak’s lawyer was cited as saying that his client’s flat was also being searched by the state investigative committee and that he was subject to legal proceedings.

“I demand the immediate release of Maxim Znak who was detained, or more accurately abducted, today. The methods employed by the so-called authorities are outrageous,” said Sviatlana Tsikhanouskaya, who ran against Lukashenko in the election and fled soon afterwards to Lithuania.

“It’s clear Lukashenko is afraid of negotiations and is trying in this way to paralyse the work of the Coordination Council and intimidate its members. But there is no alternative to negotiations, and Lukashenko will have to accept this.”

The Coordination Council quoted Znak’s lawyer, Dmitry Laevsky, as saying the state Investigative Committee had opened a criminal case against it “for inciting actions aimed at harming the national security of the Republic of Belarus”.

The Coordination Council quoted Znak’s lawyer, Dmitry Laevsky, as saying the state Investigative Committee had opened a criminal case against it “for inciting actions aimed at harming the national security of the Republic of Belarus”

State investigators were also searching the headquarters of jailed opposition politician Viktor Babariko, Interfax news agency said.

On Tuesday, prominent opposition leader Kolesnikova thwarted an attempt to deport her by tearing up her passport to avoid being forced to cross the border into Ukraine, two of her allies said.

She remains in detention, her whereabouts unknown.

WASHINGTON VOICES CONCERN

US Secretary of State Mike Pompeo said in a statement on Tuesday that Washington was “deeply concerned by the reported abduction” of Kolesnikova and two other opposition figures who were rounded up at the same time and forced to leave for Ukraine.

He called on the Belarusian authorities to “release all those who have been unjustly detained”.

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Lukashenko denies opponents’ accusations of vote-rigging and has accused foreign powers of trying to topple him in a revolution. He retains the backing of Russian President Vladimir Putin, an important ally, but faces the likelihood of European Union sanctions later this month against Belarusian officials involved in the election and its violent aftermath.

“Europe must quickly agree on a list of sanctions. And from my point of view, it should include Lukashenko, the head of this system,” Manfred Weber, a senior German conservative and head of the largest grouping in the EU Parliament, told German public broadcaster ZDF.