Ukrainian opposition leader Mikheil Saakashvili was deported to Poland on Monday, the Ukrainian border service said, after he was detained in a Kiev restaurant by law enforcement agents in camouflage.
Poland's border service confirmed that he had arrived and that Warsaw had agreed to let him enter.
The deportation appears to bring an abrupt end to a months-long cat-and-mouse game between Saakashvili and the Ukrainian authorities, which saw street unrest during previous attempts to arrest him. Some critics, including in the opposition, said his movement distracted from the broader opposition's campaign to hold the Kiev leadership to account.
"This person was on Ukrainian territory illegally and therefore, in compliance with all legal procedures, he was returned to the country from where he arrived," border service spokesman Oleh Slobodyan said in a post on Facebook.
In a statement, Saakashvili denounced President Petro Poroshenko.
"This is not a president and not a man. This is a lowlife crook who wants to wreck Ukraine. All this shows how weak they are. We will of necessity defeat them."
Saakashvili, who served as president of his native Georgia for most of the period from 2004-2013, was invited to Ukraine by Poroshenko, who took power after protests toppled a pro-Russian leader in 2014. He held a regional governorship from 2015-2016 before falling out with Poroshenko and joining the opposition.
Poroshenko stripped Saakashvili of his Ukrainian citizenship last year, but Saakashvili re-entered Ukraine anyway from Poland in September, promising to confront the president, whom he accuses of corruption, which Poroshenko denies.
Slobodyan said law enforcement officials were obliged to use force while detaining Saakashvili in Kiev as his supporters had attacked them.
A video posted on Saakashvili's official Facebook page showed several armed men in green military uniforms approaching a man lying on the floor of a restaurant.
"Such actions should not have been carried out against Saakashvili, but unfortunately they were," his spokeswoman said by telephone. She said Saakashvili's supporters would gather outside the presidential administration in Kiev at 1630 GMT to protest against his treatment.
But there was no immediate sign of public outcry, unlike in December when police tried to arrest Saakashvili but he escaped custody during street protests.
Saakashvili is wanted in Georgia on embezzlement charges that he says are politically motivated. He says he has given up his Georgian citizenship.
Saakashvili also faces criminal charges in Ukraine. The authorities accuse him of assisting a criminal organisation, which he calls a fabricated allegation to undermine his campaign to unseat Poroshenko.