Belarusian opposition leader Sviatlana Tsikhanouskaya said on Monday she's ready to lead Belarus.
Speaking in a video address from Lithuania, she called for the creation of a legal mechanism to ensure that a new fair presidential election could be held.
Tsikhanouskaya also urged security and law enforcement officers to switch sides from President Alexander Lukashenko's government, saying their past behaviour would be forgiven if they did so now.
Her video was released a day after Belarusians chanting "Step down!" filled the centre of the capital Minsk in the biggest protest so far against what they said was the fraudulent re-election a week ago of longtime president Lukashenko.
"I am ready to take responsibility and act as a national leader during this period," Tsikhanouskaya said, saying it was essential to make the most of the momentum generated by a week of protests.
The former English teacher has become one of the leading opposition figures against Lukashenko, who is struggling to contain a wave of mass protests and strikes that pose the biggest challenge to his 26-year rule of the country.
She fled abroad last week, saying she had done so for the safety of her children, but quickly began releasing new videos calling for anti-government protests to continue.
The unrest has spread to sections of society normally seen as loyal to the president, as workers from large state factories staged walkouts and some police, journalists from state media, and a sitting ambassador came out in support of the protesters.
Opponents of Lukashenko say he rigged the August 9 presidential election to secure a sixth term in power. He denies losing, citing official results that gave him just over 80 per cent of the vote.
The Kremlin said on Sunday that Russian President Vladimir Putin had told Lukashenko Moscow was ready to assist Belarus in accordance with a collective military pact if necessary and that external pressure was being applied to the country.


Russian drone strike kills 12 miners in Ukraine
Five-year-old boy returns to Minnesota after ICE release
Reopening of Gaza's Rafah crossing expected Monday
Winter storm death toll in United States reaches 90
Pakistan says 145 militants killed after attacks in Balochistan
Israeli strikes kill 26 in Gaza, health officials say
US government starts likely brief shutdown as House fails to approve deal
Thousands demonstrate in Minnesota and across US to protest ICE
