Belarus opened a criminal investigation on Thursday into attempts by the opposition to "seize power", as strongman Alexander Lukashenko moved to assert his authority after days of protests over a disputed election.

The ex-Soviet country's authoritarian leader claimed a sixth term after an August 9 ballot that sparked historic protests and a punitive police crackdown that was condemned by European leaders.

Allies of main opposition challenger Svetlana Tikhanovskaya, who says the vote was rigged and has demanded Lukashenko step down, this week formed a Coordination Council to oversee efforts for a peaceful transition of power.

The ballot sparked historic protests
The ballot sparked historic protests AFP / Sergei GAPON

The group, whose members include Nobel Prize-winning author and outspoken Lukashenko critic Svetlana Alexievich, called for a new election and talks with the authorities during its first meeting on Wednesday.

The European Union this week said it did not recognise Lukashenko's re-election and vowed to levy sanctions against what it said was a substantial number of people responsible for rigging the presidential vote and cracking down on

French President Emmanuel Macron on Thursday offered EU-led mediation for Belarus.

"A dialogue between the authorities, the opposition and civil society is essential," Macron said as he hosted German Chancellor Angela Merkel for talks at his Mediterranean presidential retreat in southern France.

The peaceful protests have been met with a brutal crackdown
The peaceful protests have been met with a brutal crackdown AFP / Sergei GAPON

Merkel, for her part, said Lukashenko "has not sought to speak" to any EU leaders about the ongoing crisis.

Meanwhile US Secretary of State Mike Pompeo offered his support to the protesters in Belarus.

"The United States has been inspired by the display of peaceful expression of the Belarusian people seeking to determine their own future," Pompeo said in a statement.

Timeline of post-electoral turmoil in Belarus
Timeline of post-electoral turmoil in Belarus AFP / Gal ROMA

Belarus Prosecutor General Alexander Konyuk said in a video statement that the Coordination Council's creation was unconstitutional and amounted to an attempt to topple Lukashenko's government.

"The creation and activities of such a council are aimed at seizing power," Konyuk said.

He announced that investigators were opening a probe into "calls for actions aimed at undermining national security", a charge that carries a maximum penalty of five years behind bars.

Lukashenko, a former collective farm director, has been in power for 26 years and defied calls to step down even after more than 100,000 people flooded onto the streets of Minsk calling for his resignation.

Lukashenko has been in power for 26 years
Lukashenko has been in power for 26 years AFP / Siarhei LESKIEC

Tikhanovskaya said she had asked Estonia's Foreign Minister Urmas Reinsalu to alert the UN security council of the investigation during a phone call.

The international community must offer "protection from potential threats and unlawful persecution," Tikhanovskaya wrote on Telegram.

Belarus' Opposition Coordination Council calls for new elections to be held "according to international standards"
Belarus' Opposition Coordination Council calls for new elections to be held "according to international standards" AFPTV / Alexander GREBENKIN

The opposition said that a member of the Council, lawyer Maxim Znak, had been summoned by investigators for questioning on Friday morning.

The 65-year-old authoritarian leader has ordered his security services to clamp down on further unrest and instructed border authorities to shore up defences against arms and money entering the country from abroad.

Security services violently dispersed peaceful protesters in the days after the vote, arresting nearly 7,000 demonstrators, with detainees accusing police of abuse and torture.

European leaders have urged Minsk's powerful ally Russia to push Lukashenko to engage in talks with Belarus's fledgling opposition.

EU Council chief Charles Michel said Thursday he had reiterated that message in a call with Russian President Vladimir Putin, adding that the only way to resolve the crisis was through talks.

"There is only one way forward: through political inclusive dialogue and a peaceful and democratic process," he wrote on Twitter.

The Kremlin has warned it could intervene if needed and Putin told Michel it was "counterproductive" to pressure the Belarusian leadership or interfere in Minsk's political processes.

Tikhanovskaya, a 37-year-old trained English teacher who contested the vote after her husband was jailed and barred from running, fled to neighbouring Lithuania after the election.

Her spokeswoman told AFP on Thursday that the EU's decision to reject the election results and impose sanctions was the "first step ... towards recognising Svetlana as the president-elect of Belarus."

Yet she warned the process of removing Europe's longest-serving leader from office may take "months".

"It's hard to keep this heat up for a long time," Anna Krasulina said. "That is why it will take a bit longer. People need to sleep, to rest"

Protesters gathered for a 12th day of demonstrations outside the Janka Kupala Theatre in the centre of Minsk on Thursday morning to voice support for its director and former culture minister Pavel Latushko.

He was forced from his post for calling for new elections and has joined the Coordination Council.

Belarus's Foreign Minister Vladimir Makei conceded on Thursday that "change is needed" in the country wedged between Europe and Russia.

"No one is denying that, but not at the cost of civil confrontation or a revolution."