Russia on Thursday issued an arrest warrant for a Georgian politician allied to President Mikheil Saakashvili accused of funding last year's street protests against Vladimir Putin.
The Investigative Committee said Georgian parliament member Givi Targamadze was accused of "preparing to organise mass disturbances on the territory of the Russian Federation together with Sergei Udaltsov" and two other leftist protest leaders.
Udaltsov was placed under house arrest in connection with the same investigation last week. He faces up to 10 years in jail if put on trial and convicted.
Targamadze sits in the Georgian parliament as a senior member of the opposition United National Movement Party of Saakashvili -- a top foe of Putin's Kremlin after the 2008 Moscow-Tbilisi war.
The charges stem from a documentary-style film attacking the opposition movement that was broadcast on Russian government-controlled NTV television on October 5.
"The Anatomy of a Protest -- 2" showed grainy footage of a figure resembling Udaltsov meeting with a group of people who included a man with a Georgian accent.
The film alleged that a Moscow banker on poor terms with the Kremlin had volunteered to finance the street protests while Targamadze acted as the middleman in the talks with Udaltsov.
Both men deny the charges.
The Investigative Committee -- Russia's nearest equivalent of the US Federal Bureau of Investigation (FBI)-- said it was issuing the arrest warrant after officially being informed by Tbilisi that Targamadze had no immunity from prosecution.
But the Georgian prosecutor general's office said that Targamadze could not be handed over to Moscow, for reasons it did not explain.
"All we can do is start a criminal investigation upon Russia's request," said a spokesman for the office, Khatuna Paichadze.
"This is customary international practice," the Georgian official said.
Udaltsov represents the more militant wing of a broad protest movement that includes more popular figures such as the anti-corruption campaigner Alexei Navalny and the socialite-turned-opposition figure Ksenia Sobchak.
Some 100,000 people came out in Moscow at the height of the protests at the start of last year.
The movement has lost most of its steam since Putin's overwhelming election to a third term in March and no more than 20,000 have been turning out for the latest rallies in the capital.