"They did it against all the rules, what's happening here?"
Saakashvili traveled to Lviv after crossing the border, but his whereabouts today are not clear.
"We hope we can still get there", Saakashvili told reporters at the Medica border crossing. Government officials at the border said 17 police and guards were injured during the confrontation with Saakashvili's supporters. Ukrainian authorities in the border region tried to block Saakashvili's return - first by train, then by bus - but then he walked across the Ukrainian border at Shehyni in the midst of a crowd of his supporters.
He said Saakashvili should have contested the decree stripping him of citizenship in court if he disagreed with it.
Earlier on Sunday, Ukrainian authorities blocked a Kiev-bound train in Poland carrying Saakashvili, who eventually got off and took a bus to the Medyka crossing.
Supporters of the Former Georgian President and former Ukraine official Mikheil Saakashvili clash with border guards at Shegini check point on Ukrainian-Polish border, Ukraine, Sunday, Sept. 10, 2017.
After having led Georgia for a decade, Saakashvili, who had been criticized for his authoritarian style and especially to the disastrous war with Russian Federation in 2008, had acquired Ukrainian citizenship in 2015, and was appointed governor of the Ukrainian region of Odessa (south). It left him effectively stateless as Georgia has also withdrawn his citizenship.
The Georgian prosecutor's office repeatedly called for Kiev to extradite Saakashvili, but the Ukrainian side rejected the appeals at least twice.
Saakashvili's relationship with Poroshenko dates back almost three decades to when they were students at the same university in Kiev and their shared opposition to the Kremlin later brought them together as politicians. "We will perform border checks once the train departs", she said.
Ukraine's migration service said the president takes decisions on who is stripped of Ukrainian citizenship based on the conclusions of the citizenship commission.
"This passport is not the plaything of individual oligarchs, who issue it and then retract it, declare it invalid or use it to blackmail you", Saakashvili recently protested, threatening he would return to Ukraine soon, speaking to Der Spiegel.
Georgia has pursued Saakashvili on criminal charges of abuse of power and misappropriation of property. "Right now, it is important for us, as opposition leaders and European democratic powers, to unite and to stop the new corrupt-dictatorship establishment in Ukraine".
Ukrainian President Petro Poroshenko wants punishments to be handed down for the Saakashvili-supporters who barged across the border to bring Saakashvili across from Poland.