Burjanadze, the ex-parliamentary speaker turned opposition leader, said a 'revolution' had started in Georgia [AFP]
Several hundred activists in Georgia have called for the country's president to resign, extending protests into a third day.
The demonstrators accuse Mikheil Saakashvili of authoritarianism and failing to tackle widespread poverty.
The protesters are maintaining a round-the-clock rally outside the country's public television studios in Tbilisi, the capital.
Many were armed with sticks on Monday after brief clashes a day earlier when police used rubber bullets and tear gas against demonstrators who attacked cars.
"We will stay here until they throw us out. They could crack down at any time," said Lasha Oniani, a protester.
Nino Burjanadze, the former parliamentary speaker turned opposition leader, said a "revolution" had started in Georgia.
'Day of Rage'
Echoing language used to rally protesters in the uprisings in the Arab world, Sozar Subari, chairman of the opposition Georgian Party, said: "We are calling our supporters to come to the rally on May 25 and we call this day 'Day of Rage'."
The protesters are hoping to repeat the success of the Arab Spring rallies but observers say the country's opposition is fractured and has so far failed to overcome internal squabbling to be able to engineer an uprising.
Despite poor social conditions and the country's disastrous defeat in a war with its arch-foe Russia in 2008, the current protests have so far failed to attract significant numbers of people.
Several thousand people rallied on Saturday in Tbilisi and hundreds in the Black Sea resort city of Batumi, but turnout fell to around 2,000 on Sunday.
"There is no sign of a revolutionary situation in Georgia," said David Darchiashvili, a senior governing party politician.
"They want to have a [Egyptian-style] Tahrir Square [revolt] in Georgia, but this has nothing in common with reality."
Irakli Okruashvili, the fugitive former defence minister turned opposition leader, who was granted political asylum in France, has vowed to arrive in Georgia this week to join the Wednesday rally despite facing an 11-year jail sentence for alleged corruption.
Officials said that Okruashvili, whose arrest helped to spark mass protests after he turned against the Georgian president in 2007, would be detained immediately.
"We will be glad to allow him to start his sentence," said Shota Utiashvili, the interior ministry spokesman.
Saakashvili was swept to power after ousting his predecessor Eduard Shevardnadze during the non-violent "Rose Revolution" in 2003, vowing to tackle institutional corruption and win membership of NATO.
But his ambitions brought him into conflict with Russia, with the Kremlin recognising rebel Georgian regions Abkhazia and South Ossetia as independent states after the war in 2008.
Tbilisi describes Russia's presence in the regions as an "occupation".
Saakashvili's administration sent in riot police to crush opposition protests in 2007, at a time when current opposition leader Burjanadze was a senior government official.
The authorities say the current rallies will be allowed to continue unhindered as long as they remain peaceful.
"It would not seem to be in the government's interest to crack down because of the small numbers of demonstrators," said Lawrence Sheets, a Tbilisi-based analyst from the International Crisis Group think tank.
Opposition leaders are hoping to force Saakashvili to resign ahead of parliamentary elections in 2012 and presidential polls the following year.
Despite the war and political turmoil, he has remained the country's most powerful figure and many believe that he could continue to dominate Georgian politics after his term ends in 2013.