Demonstrators have swarmed the streets daily to contest the official results of Sunday's vote that showed authoritarian President Alexander Lukashenko extending his 26-year rule with 80 per cent of the vote.

Nearly 7000 people have been detained and hundreds injured since Sunday as police ferociously dispersed demonstrations with stun grenades, tear gas and rubber bullets.

Many of those released talked about brutal beatings and other abuse at the hands of police, and some showed bruises.

The releases come as European Union foreign ministers are due to meet to discuss possible sanctions against Belarus.

Lukashenko's main challenger, Sviatlana Tsikhanouskaya, who has taken refuge in neighbouring Lithuania, posted a video statement contesting the results of the vote and demanding the government launch a dialogue with protesters.

Thousands of workers have joined the protests, demanding a new election and raising the prospect of a nationwide strike.

"Our entire shop voted against Lukashenko and then we suddenly learned that he won by a landslide," 42-year-old assembly worker Dmitry Glukhovsky said outside the Minsk Automobile Plant.

"They not only have cheated us but also beaten us up, and no one is going to accept that."

Clearly nervous, the Belarusian leader, warned on Friday the strikes would deepen the damage inflicted by the coronavirus pandemic and could lead to Belarus losing its niche in global markets.

"Everyone is fighting for markets, and if we stop we will never be able to resume production," he said.

Valiantsin Stefanovich of the Viasna rights centre confirmed that about 1000 people had been released from jails.

"The authorities are obviously trying to de-escalate the situation and ease the tensions, fearing that the furious industrial workers will take to the streets all across Belarus," Stefanovich said.

Police stood back on Thursday and Friday as thousands of people formed "lines of solidarity" in Minsk and other cities.

In a video statement released on Friday, Tsikhanouskaya challenged Lukashenko's victory, saying copies of protocols from precincts where the vote was counted fairly show her winning 60-70 per cent of the vote.

"The Belarusians will never want to live under the current government," she said. "The authorities have turned peaceful demonstrations into a blood bath."

A protester died on Monday in Minsk when, according to the Interior Ministry, an explosive device he tried to throw at police blew up in his hand.

Media reports challenged the ministry's claim, alleging that he was killed by police.

Ahead of the meeting of EU foreign ministers to discuss sanctions against Belarusian officials responsible for the crackdown, German Chancellor Angela Merkel's spokesman Steffen Seibert told reporters the peaceful protests "reflect the dissatisfaction, the anger and the desperation" of people in Belarus and the government's crackdown was "completely unacceptable."

Australian Associated Press