Facing the biggest challenge of his 26 years in power, Lukashenko said on Saturday he had won support from Russian President Vladimir Putin who promised help to "ensure the security of Belarus".

The Kremlin said only that the leaders had agreed in a phone call that the "problems" in Belarus would be "resolved soon", with no mention of specific support for Lukashenko.

The Belarusian strongman, who has ruled his ex-Soviet country with an iron grip since 1994, is under increasing pressure from the streets and abroad over his claim to have won re-election last Sunday with 80 percent of the vote.

Tens of thousands have taken to the streets to denounce the result and support the main opposition challenger Svetlana Tikhanovskaya, a 37-year-old political novice who ran after other potential candidates including her husband were jailed.

A violent police crackdown on protesters has seen more 6,700 people arrested, hundreds wounded and two people dead.

From exile in Lithuania, where she fled on Tuesday, Tikhanovskaya called for a weekend of peaceful rallies including Sunday's march in Minsk on the one-week anniversary of the vote.

The opposition has called for one of the biggest rallies yet in defiance of Lukashenko, who has dismissed protesters as foreign-controlled "sheep" and criminals.

A pro-government demonstration has also been called from midday, a few hours before the opposition march is set to begin. There were reports of workers being required to attend the demonstration or risk losing their jobs.

On Friday hundreds of workers at state-run factories walked off the job in protest at the election, in a first sign that Lukashenko's traditional support base was turning against him.

Thousands of opposition supporters demonstrated in Minsk on Saturday, with many gathering at the spot where a 34-year-old protester died during unrest on Monday.

Fears of Russia intervention

Demonstrators heaped flowers at the spot and the crowd chanted "Thank you!" and raised victory signs.

Many held up photographs of protesters beaten during the crackdown, while one man stood in his underwear revealing the purple bruises on his thighs, buttocks and back.

Amnesty International has accused authorities of carrying out "a campaign of widespread torture" to crush the opposition.

Some protesters said they feared a Russian intervention on Lukashenko's behalf.

"It's obvious that our president can't deal with his own people any more, he's seeking help in the east," said Alexei Linich, a 27-year-old programmer.

"If Russia intervenes, that would be the worst. I'm really afraid of this," said Olga Nesteruk, a landscape designer.

Thousands also protested on Saturday evening outside the Belarusian state television centre, complaining that their broadcasts backed Lukashenko and gave a skewed picture of the protests. Around 100 staff came out of the building to join the crowd, and said they planned a strike on Monday.

European governments have condemned the election and police crackdown, and EU ministers on Friday agreed to draw up a list of targets in Belarus for a new round of sanctions.

The leaders of the three ex-Soviet Baltic states -- Estonia, Lithuania and Latvia -- on Saturday called for a new vote.

Tikhanovskaya has announced the creation of a Coordination Council to ensure a transfer of power, asking foreign governments to "help us in organising a dialogue with Belarusian authorities".

She demanded the authorities release all detainees, remove security forces from the streets and open criminal cases against those who ordered the crackdown.

She has said she will organise new elections if Lukashenko steps down.

Lukashenko on Saturday rejected any foreign mediation in the crisis and told defence chiefs he would not hand over power.

"We will not give up the country to anyone," he said. "We don't need any foreign governments, any intermediaries."

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