Saakashvili, a former Ukrainian governor, fell out with Ukrainian President Petro Poroshenko and was stripped of his Ukrainian passport.
He forced his way back into the country with the help of supporters in September and has since led rallies calling for Poroshenko’s ouster.
The 49-year-old politician’s confrontation with Ukrainian authorities came to a head yesterday morning when police raided Saakashvili’s flat, prompting him to climb onto the roof of his central Kyiv building and address supporters below before officers led him down into a vehicle.
Ukraine’s general prosecutor Yuriy Lutsenko accused Saakashvili and his allies of receiving $500,000 (€420,000) from Russian sources to fund the rallies against the pro-Western Ukrainian government.
Lutsenko claimed that Saakashvili was in cahoots with the allies of former Ukrainian president Viktor Yanukovych, who he said plotted “revenge” from Russia where he had fled after being removed from power in a popular uprising in 2014.
Ukraine is fighting a Kremlin-backed separatist movement in the east of the country in a conflict that has claimed more than 10,000 lives since 2014 and accusations of ties with Moscow are hugely damaging in the eyes of voters.
Saakashvili called Lutsenko’s claim a “provocation”.
After his detention, several hundred people gathered around the van carrying the politician and prevented it from moving, finally freeing him from it.
Amid clashes, police and Saakashvili supporters used tear gas against each other.
After emerging from the van with one hand handcuffed, Saakashvili urged his supporters to march to the Ukrainian parliament and demand the impeachment of the president.
“There are millions of us, we are very strong,” he said.
Speaking earlier from the roof, he accused Poroshenko of being a thief and “a traitor to the people of Ukraine”.
“I call on all decent Ukrainians to take to the streets and drive out these thieves. I call on Ukrainians not to allow me to be abducted, I appeal to the people of Kiev not to allow lawlessness.”
He must appear before investigators this morning, prosecutors said.
The charismatic politician is credited with pushing through pro-Western reforms in his native Georgia which he led from 2004 to 2013 after rising to power during the so-called “Rose Revolution” in 2003.
Observers say however that there is little appetite for new turmoil in Ukraine, which has gone through two popular uprisings since 2004.
But Iryna Bekeshkina, head of the Kyiv-based Democratic Initiatives Foundation, said that despite Saakashvili’s insignificant approval ratings, the arrest could have a wider effect.
“The problems Saakashvili is exploiting, they really exist,” she wrote on Facebook, describing the situation as “explosive”. “Corruption, thefts worth millions, impunity of criminals and much more.”
In the wake of the pro-Western revolution in Kyiv, Saakashvili moved to Ukraine in 2015 to work as governor of the key Odessa region on the Black Sea.
Relations with Poroshenko soured over accusations that Kyiv was failing to make good on the fight against corruption.
Saakashvili hopes his political party will grab seats from the president’s increasingly unpopular group in polls set for 2019.
Moscow officials could hardly contain their glee over the new turmoil in Kyiv, with President Vladimir Putin’s spokesman saying that Saakashvili “has come a long way from chewing his tie to climbing on the roof. It has been a thorny path”.
The then-Georgian leader famously gnawed on his tie as he waited to be interviewed in 2008, during the Georgia-Russia war, in footage widely broadcast in Russia.
Putin famously derided Saakashvili at the time.
Asked to comment on the situation in Kyiv, Putin spokesman Dmitry Peskov said: “We are not used to responding to the statements of people sitting on roofs.”
Saakashvili is a top enemy of Putin, with the two locking horns during a five-day war between Georgia and Russia in August 2008.
Carl Bildt, the co-chair of the European Council on Foreign Relations, said the news of the arrest was “disturbing”.
“Political arrests will radically diminish the country’s credibility in the West. That’s a security issue at the end of the day,” the former Swedish prime minister said via Twitter.
The US embassy in Kyiv called “for all sides to deescalate tensions and avoid violence”.
A woman climbs on the roof of the police van in which Saakashvili was transported as his supporters prevent the vehicle from moving.
