Belarus opposition leader Svetlana Tikhanovskaya has called for peaceful rallies across the country, after she was forced to leave for Lithuania in the wake of a disputed election.
"Don't stay on the sidelines," she said, proposing a broad council to work on the transfer of power.
Alexander Lukashenko has ruled Belarus since 1994 but Sunday's presidential vote was condemned by the EU and US.
Protests have erupted across the country calling for him to quit.
Some 6,700 people were arrested in the wake of the election, and many have spoken of torture at the hands of the security services.
As protests continued for a sixth day and walkouts from state factories grew on Friday, EU foreign ministers held an emergency video meeting and agreed to prepare new sanctions on Belarusian officials responsible "for violence and falsification".
Amnesty International said accounts from released detainees suggested "widespread torture".
Russia on Friday said Belarus had handed back 32 suspected mercenaries who had been detained since last month. Authorities in Belarus said the men were in the country to destabilise Sunday's election, while Russia said they were just passing through. Details of their release are not yet clear.
Ms Tikhanovskaya was held for seven hours herself on Monday night, when she went to register a complaint about the election, before she was forced into exile.
The Central Election Commission says Mr Lukashenko won 80.1% of the vote and Ms Tikhanovskaya 10.12%.
But Ms Tikhanovskaya insists that where votes were properly counted, she won support ranging from 60% to 70%. She has called on mayors to organise "peaceful mass gatherings" on Saturday and Sunday.
'I begged him to stop but he continued'
By Abdujalil Abdurasulov, BBC News, Minsk
Sergiy was detained on Monday. Riot police threw him into a police van and started torturing him.
They kept asking who the organiser was and each time when he said that there was no such a person, they electrocuted him with a stun gun. For every word he tried to say, they beat him with batons in response.
"The scariest part was that these people knew no limits," he said.
"You understand you're totally without any rights, that they could do anything they wanted. The pain was unbearable and I begged him to stop but he continued."
After hours of torture, Sergiy could barely breathe. Officers called an ambulance and sent him to hospital. Otherwise he might not have survived the notorious Okrestina detention centre.
Many have faced more vicious beatings and the mistreatment of detainees remaining in prisons continues. Volunteers outside the detention centre in Minsk on Friday asked us to be quiet and urged people not to clap and chant to support the detainees. They say that otherwise those who remain behind the prison walls will get beaten in revenge.
Prisoners continued to be released from the notorious Okrestina detention centre in Minsk on Friday, revealing their bruised and swollen bodies.
"They beat people ferociously, with impunity, and they arrest anyone. We were forced to stand in the yard all night. We could hear women being beaten. I don't understand such cruelty," one man said as he showed the BBC his bruising.
Belarus Interior Minister Yuri Karayev said he took responsibility for people being injured and wanted to apologise to people caught up in the violence.
Russian journalist Nikita Telizhenko wrote a harrowing account of his three days inside prison, detailing people lying on the floor of a detention centre, piled on top of each other, in a pool of blood and excrement. They were not allowed to use the toilet for hours on end or even change position.
What is opposition leader proposing?
Ms Tikhanovskaya, who arrived in Lithuania on Tuesday, said in her video message that Belarus authorities should stop violence and "engage in dialogue" and her supporters should sign an online petition calling for a vote recount.
In a separate message she praised Belarusians for showing "we are a majority and this country belongs to us, to the nation rather than one man". She then called for:
- a co-ordinating council made up of "civil society activists, respected Belarusians and professionals" to secure a transfer of power
- involvement from personnel from industrial companies, trade unions and other civil society organisations
- the international community and European states would help organise dialogue with Belarus authorities
- authorities should free all detainees, remove riot police and troops from the streets and prosecute those who ordered violence.
Ms Tikhanovskaya, 37, only entered the presidential race after her husband was arrested and blocked from registering for the vote. Her statements on Friday were a far cry from her last message on Tuesday, when she said she had left Belarus for the sake of her children and spoke of herself as "a weak woman".
More about the protests in Belarus
- LETTER FROM MINSK: Shocked by violence, people lose their fear
- SPREADING THE NEWS: How messenger app bypassed blackout
- PROFILE: The stay-at-home mum challenging Belarus's longtime ruler
What is happening on the ground?
Belarusians returned to the streets of several cities on Friday. In the western city of Grodno, workers gathered outside a management office, demanding fresh elections, and car workers gathered in big numbers at the Maz plant in Minsk. Walkouts were also reported at a number of other factories.
Mr Lukashenko, who has previously dismissed protesters as sheep condemned "attempts to inflame workers" and spoke of walkouts involving 20 people.
Tractor workers taking part in a big march in Minsk on Friday carried a banner reading: "We're not sheep, we're not a herd, we're not little people... there are not 20 of us but 16,000."
EU foreign ministers agreed on Friday to draw up a list of people to be targeted with sanctions. The bloc, which has condemned Sunday's vote as "neither free nor fair" has imposed sanctions before but eased the measures four years ago when President Lukashenko released other detainees.
Czech Prime Minister Andrej Babis said sanctions should be imposed "until free and transparent elections are held in Belarus with the participation of international observers". Poland has promised to loosen visa restrictions on its neighbour to help support civil society.
Ahead of the emergency EU meeting, Belarus Foreign Minister Vladimir Makei said his country was ready for "constructive and objective" talks with other countries.