MOSCOW (AP) -- Hundreds of protesters clashed with police in Kiev and called for the ouster of Ukraine's president following a botched attempt Tuesday by authorities to arrest Mikheil Saakashvili, a former Georgian president-turned-Ukrainian opposition leader.
The turmoil is just the latest challenge for the Ukrainian government, which has been weakened by months of political infighting and accused of not halting official corruption.
Tuesday's standoff began when officers of Ukraine's Security Service, the SBU, went to Saakashvili's home in Kiev to detain him. Trying to resist the arrest, he climbed onto the roof and threatened to jump off, but SBU agents took him down and put him into a van.
Several hundred protesters then surrounded the vehicle and blocked it from moving. They clashed with police, who unsuccessfully tried to disperse the demonstrators with tear gas.
After a tense standoff that lasted for hours, Saakashvili was freed by his supporters and led them on a march to parliament to demand President Petro Poroshenko's resignation.
"I will die for Ukraine," Saakashvili shouted to the crowd. "I owe you my freedom and my life."
With the yellow-and-blue Ukrainian flag around his neck, Saakashvili urged Ukrainians to rise against "Poroshenko and his gang."
"Don't be afraid, let them fear us!" he shouted.
Saakashvili has won broad popularity in Ukraine with his fiery campaign against official corruption, riding a wave of public frustration over Poroshenko's failure to uproot endemic graft. He has staged a series of rallies calling for the president's resignation, but they haven't produced any visible impact.
Ukrainian Prosecutor General Yuri Lutsenko claimed on television that his office has evidence that Saakashvili's representative received $500,000 from Ukrainian businessmen who have ties to Russia to finance the protest.
Saakashvili rejected the accusation, noting the long-running hostility between him and Russian President Vladimir Putin. When he was president of Georgia, Saakashvili made a failed attempt to reclaim control over Georgia's separatist province of South Ossetia, triggering a five-day war with Russia in 2008. He has repeatedly mentioned Putin's reported threat to have him hanged.
Saakashvili won quick support from Tuesday other Ukrainian opposition leaders, including former Prime Minister Yulia Tymoshenko. Speaking in parliament, Tymoshenko criticized the SBU's attempt to arrest Saakashvili as "political terror."
Oksana Syroyed of the Self Reliance Party also denounced the attempted arrest as an action by a "despotic machine."
But while opposition leaders expressed support for Saakashvili, their activists stayed away from the street protest, reflecting a cautious stance toward a potential competitor.
"Opposition parties see him as a rival and aren't in a hurry to support the protest," said Volodymyr Fesenko, a Kiev-based political analyst.
Fesenko also said while Saakashvili has enough support to stage rallies, he lacks the power to force a government change.
"They can make a lot of noise, but most Ukrainians are wary of the negative and unpredictable consequences of a new Maidan," Fesenko said, referring to the 2014 protests on Kiev's main square that drove out Ukraine's former Russia-leaning President Viktor Yanukovych.
Poroshenko named Saakashvili as governor of the Odessa region in 2015, but he stepped down the following year after falling out with the president. Earlier this year, Poroshenko stripped him of Ukrainian citizenship while he was out of the country, but Saakashvili came back in September, helped by supporters who broke through a police line at the Polish border.
The tensions in Kiev come as fighting continues between Ukrainian forces and Russia-backed separatists in eastern Ukraine. The conflict, which erupted after Russia's 2014 annexation of Crimea, has left more than 10,000 people dead since then.
The Kremlin, meanwhile, was clearly relishing the turmoil in Kiev.
"We are watching those developments with interest," Putin's spokesman Dmitry Peskov told reporters. "It's Ukraine's headache. It's something you wouldn't wish to even your enemy, but, of course, we don't consider the Ukrainian people our enemy."