A Georgian opposition party, Justice, called Thursday for a national disobedience campaign to topple the president and his government, as 14 party activists were charged with preparing a coup.
The defendants' lawyers said their clients are innocent.
The Georgian Prosecutor General's Office asked the court to remand them in custody for two months pending trial to provide incontrovertible proof of their guilt.
If no evidence is produced in that time, under the Georgian Code of Criminal Procedure the defendants will be freed immediately in the courtroom itself.
The interior minister said Wednesday the country's law enforcement agencies have information that supporters of controversial former Georgian minister and security chief Igor Giorgadze were preparing to overthrow the government, and were making arrangements for Giorgadze's return from exile.
In all, 29 people were detained in raids, and 14 individuals who remained in custody Thursday were officially charged.
But Justice party representative Irina Sarishvili told a news conference her party would seek to bring down President Mikheil Saakashvili, who himself came to power on the back of popular protests, and his government.
"We propose setting up a national disobedience movement and starting large-scale actions with only one demand -- that the country's current leadership resign," said Sarishvili, who runs the Igor Giorgadze Foundation in Georgia's capital, Tbilisi.
Justice party leader Giorgadze himself is said to be living in Russia after fleeing the country in 1995, when he was accused of organizing an assassination attempt on then-president Eduard Shevardnadze. He has denied the claims.
Georgian law enforcement agencies carried out an operation Wednesday to arrest supporters of Giorgadze, his Justice party and other public and political organizations, including the leader of the opposition Conservative Monarchist party, Teimuraz Zhorzholiani, and of the Anti-Soros political movement, Maya Nikoleishvili.
President Saakashvili told journalists the alleged plotters would be dealt with harshly. "They will get what they deserve, and those who finance them can be sure of that," he said.
But Sarishvili rejected a statement by the Georgian Interior Ministry about an alleged conspiracy aimed at overthrowing the authorities at a party conference May 4. "There was no conference and, of course, no plan to overthrow the authorities," she said.
The detained activists protested their innocence and said their political work led to their arrest, which prompted Sarishvili to say the detentions looked like the start of a campaign of political repression.
A senior Russian diplomat said Moscow, which has had tense relations with Tbilisi since the 2003 "rose revolution" brought Saakashvili to power, regards the arrests as an internal matter for Georgia.