Thousands took to the streets of Tbilisi on Saturday to demand the resignation of President Mikheil Saakashvili.
The opposition marchers accuse Saakashvili of authoritarianism, claiming he has failed to tackle widespread poverty.
They also say he is responsible for losing huge swathes of Georgian land in a conflict with Russia in 2008.
Nino Burjanadze, a former ally of the president, told the crowd:
“We will fight to the end together with you, however difficult the fight may be. We will not take a single step back and we will make this government step down. This is a decisive fight.”
In the autonomous Black Sea town of Batumi, a crowd of around 400 mobbed the HQ of the local state television.
Russian news agencies reported that police opened fire on protesters.
Witnesses say the authorities did not use weapons but clashed with the demonstrators before the gathering was broken up.