Georgian opposition leaders on Friday vowed to hold mass protests until parliament is dissolved, after police used rubber bullets and tear gas against demonstrators who had rallied overnight.
Demonstrations broke out in capital Tbilisi on Thursday after a Russian lawmaker addressed parliament from the speaker's seat -- a deeply controversial move in a country at loggerheads with Moscow.
"The Georgian people and opposition parties demand snap parliamentary polls as well as the resignation of the speaker and the interior minister," Grigol Vashadze, the leader of the United Opposition alliance, told AFP.
"Peaceful mass protest will continue until these demands are met," he said, adding that a fresh rally would start at 7 pm (GMT 1500) on Friday.
The Kremlin on Friday condemned the protests as "aggressive demonstrations against citizens of Russia".
The presence of Russian MP Sergei Gavrilov in parliament sparked outrage in the ex-Soviet nation which in 2008 fought and lost a war with Moscow over the breakaway regions of Abkhazia and South Ossetia.
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But with parliamentary polls set for next year, opposition groups are also seeking to capitalise on discontent with the ruling Georgian Dream party over its failure to kick-start a stagnant economy.
About 10,000 protesters gathered outside parliament on Thursday afternoon after Gavrilov addressed a forum of lawmakers from predominantly Orthodox countries.
Police pushed back demonstrators when they attempted to enter the parliament courtyard but overall the rally continued peacefully until midnight when officers launched a violent crackdown.
Ambulances evacuated dozens of injured protesters, an AFP reporter at the scene said.
An adviser to Georgian Prime Minister Mamuka Bakhtadze said 39 police officers and 30 protesters were hospitalised.
Hundreds of baton-wielding riot police intervened again, beating up and arresting dozens of protesters.
Human Rights Watch criticised the use of tear gas and rubber bullets "against thousands of non-violent protesters".
Police failed to "abide by human rights for the use of force," the group said.
Georgian President Salome Zurabishvili described Gavrilov's Russian-language speech as "a crime...an offence against the country's dignity".
"But this can't justify anti-state actions, calls to storm parliament and overthrow the government," she said in a statement Thursday as she cut short a trip to fellow ex-Soviet republic Belarus.
Prime Minister Bakhtadze said "destructive opposition leaders" who "staged mass violence" would face justice, in a late-night televised address to the Caucasus mountain nation.
Oligarch Bidzina Ivanishvili -- widely believed to be calling the shots in the country as leader of the Georgian Dream party -- said he "fully shares the sincere outrage of Georgians" over the invitation to the Russian representative.
Ivanishvili said he had told the parliamentary speaker to suspend the forum of Orthodox nations' MPs.
Mass protests are relatively common in Georgia, where tens of thousands rallied last year over alleged irregularities in a presidential election.
A 2003 "Rose Revolution" pushed out the country's Soviet-era leadership and brought in reformer Mikheil Saakashvili, who served until 2013 and now lives in self-imposed exile as a Ukrainian citizen.
Relations between Georgia and its Soviet-era master Russia have long been fractured over Tbilisi's bid to join the European Union and NATO.
The confrontation culminated in a full-out war in August, 2008.
The Russian army swept into Georgia -- bombing targets and occupying large swathes of territory -- after Tbilisi launched a military operation against South Ossetian separatist forces who had been shelling Georgian villages.
After the war, which claimed the lives of hundreds of soldiers and civilians from both sides, Moscow recognised South Ossetia and another separatist enclave, Abkhazia, as independent states where it then stationed permanent military bases.
Tbilisi and its Western allies have denounced the move as an "illegal military occupation.