Ukrainian border-control authorities have formally read out a document to Mikheil Saakashvili on his illegal entry into Ukraine two days earlier.
Saakashvili was served the notice on September 12 in front of a group of journalists and lawmakers outside of a hotel in Lviv, with police and border guards on hand.
Ukraine's state-run Ukrinform news agency reported that Saakashvili signed the document, acknowledging the allegations of an "administrative violation," during the meeting outside the Leopolis hotel in central Lviv, where he has been staying since September 10 when he and supporters broke through a line of Ukrainian border guards to cross from Poland to Ukraine.
The Ukrainian Interior Ministry was later quoted by the Interfex news agency as saying that Saakashvili was in the country illegally but authorities were not intent on detaining him at the moment.
Police arrived at the hotel on the morning of September 12 and initially blocked access to the building in Lviv, whose mayor, Andriy Sadovyy, has clashed with President Petro Poroshenko in the past.
The State Border Guard Service confirmed the operation was aimed at serving Saakashvili with the document.
Saakashvili said in Lviv on September 12 that the document should have been delivered to him earlier.
"If they brought this protocol within three hours when we crossed the border...they could not say that I was hiding somewhere. I was on the main square of Lviv, along with thousands of [people], I would have taken this protocol without question. But what they bring now is a violation of the law," Saakashvili said.
He also said he would travel to Kyiv "within days, or weeks" after visiting "towns and villages" across Ukraine.
A day earlier, Saakashvili said he wanted to unite Ukraine's opposition against Poroshenko and that he planned to campaign for support.
Poroshenko had appointed Saakashvili to govern Ukraine's Odesa region in 2015. But Saakashvili resigned from the post in November 2016 after falling out with Poroshenko, complaining that his reform efforts were being blocked.
In July, Poroshenko issued a decree that stripped Saakashvili of his Ukrainian citizenship.
That left the former Georgian president essentially stateless because Georgia stripped him of Georgian citizenship in 2015 when he obtained Ukrainian citizenship in order to take the Odesa post.
On September 11, Ukrainian Interior Minister Arsen Avakov said Saakashvili faced "serious" criminal charges for his border breach, which Avakov described as "an attack on the state's basic institutions."
Under Ukrainian law, the penalty could be up to five years in prison.
Sixteen security personnel were injured in clashes with Saakashvili's supporters during the incident on the Polish-Ukrainian border.
Two Saakashvili supporters -- Oleksandr Burtsev and Andriy Kotichenko -- were detained by police on September 12 for their alleged role in the border violence, according to the Ukrainian Interior Ministry.
Saakashvili, who is wanted in Georgia on allegations of corruption and abuse of power, claims to have UNHCR recognition as being "stateless."
He says he wants to challenge the revocation of his citizenship before a court in Ukraine.