Mikheil Saakashvili, who was freed from police custody shortly after law enforcement authorities raided his apartment in Kyiv earlier this week, is calling on Ukrainians to demonstrate in the center of the capital on December 10.
In a Facebook post late on December 7, Saakashvili told supporters he had lost his voice and was running a temperature but would "be by your side again" at a midday march to Kyiv's Maidan Nezalezhnosti, or Independence Square, on Sunday.
Saakashvili -- the former Georgian president who became governor of Ukraine's Odesa region in 2015 but quit a year later and is now a vocal opponent of President Petro Poroshenko -- thanked backers for their support in the tumult of recent days.
Law enforcement officers searched Saakashvili's apartment in Kyiv on December 5, dragged him off the roof, and bundled him into a car. But supporters blocked the streets and pulled him from the vehicle, and he led a march to parliament.
Police raided a protest tent camp near parliament early on December 6, but Saakashvili was not detained and a 24-hour deadline for him to turn himself in passed without visible action by the authorities.
WATCH: Ukrainian security forces arrested former Georgian President Mikheil Saakashvili on suspicion of assisting a criminal organization but he later escaped from custody in Kyiv with help from his supporters. (RFE/RL's Ukrainian Service)
Ukrainian officials have accused Saakashvili of abetting an alleged "criminal group" led by former Ukrainian President Viktor Yanukoych -- who was pushed from power in 2014 by protests on Independence Square and fled to Russia -- and have suggested that his protests are part of a Russian plot against Ukraine.
Saakashvili -- a Kremlin foe whom Russian leaders accuse of provoking the five-day war between Moscow and Tbilisi in 2008, when he was Georgian president -- has dismissed the claims.
The search of Saakashvili's home was conducted two days after his Movement of New Forces party organized a rally in Kyiv calling for Poroshenko's impeachment and for legislation that would allow it to take place.
Poroshenko late on December 8 said international experts may help justice officials investigate the charges against Saakashvili, adding that he was sure Saakashvili would get a fair trial in Ukraine.
"I don't exclude that the inquiry may ask for extra expertise, including from international organizations, to enhance trust," Poroshenko told reporters during a visit to Vilnius to meet with Lithuanian President Dalia Grybauskaite.
Saakashvili "has to answer to investigators and to society regarding the accusations against him," Poroshenko said. "If he doesn't answer, it only means that these accusations are well-founded."