Saakashvili crossed into Ukraine in an attempt to regain his Ukrainian citizenship of which he was stripped in July.
Ukrainian police launched criminal proceedings into the illegal border crossing of former Georgian president and Odessa governor Mikhail Saakashvili, during which he and his supporters publicly forced their way through a cordon on the Polish border, RT reports.
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. Two months ago, Poroshenko personally signed an order annulling Saakashvili's citizenship, though no official reason was made public.
Speaking to reporters in Rzeszow, the 49-year-old Saakashvili said that Poroshenko's actions, "the way how he mobilized the whole of the state apparatus" against him, "means that he feels some existential threat" from the former Georgian president.
In Georgia between 2004 and 2013, he was credited with pushing through pro-Western and anti-graft reforms.
Saakashvili said the decision was politically motivated.
"It does not matter who violates the state border - invaders in the East or politicians in the West".
The return carries risks for Saakashvili, who is stateless.
Mikheil Saakashvili, the former president of Georgia, ended up being the catalyst for a train from Poland to Ukraine being held up by Ukrainian guards at a checkpoint. According to the border police, 12 policemen and five border guards suffered in clashes with guards of Saakashvili. "This is a matter of national security", Poroshenko said.
Meanwhile, Ukraine's Interior Minister Arsen Avakov says that Mikheil Saakashvili should fill the form of the border-crossing fact at the Shehyini checkpoint or immigration service.
Saakashvili said the border guards refused to take his passport from him and stamp it to enter the country.
The stateless Saakashvili had initially meant to travel through the Krakovets border crossing where hundreds of supporters of his Movement of the New Forces party had gathered.
"I hope [Saakashvili] will be just as eager to go to Georgia as he was to get into Ukraine", Poroshenko added, an allusion to criminal charges the pro-Russian government in Tbilisi has leveled against him at home.
He said Saakashvili should have contested the decree stripping him of citizenship in court if he disagreed with it.