Mikheil Saakashvili tendered his resignation as governor of Ukraine's southern Odessa region on Monday, accusing president Petro Poroshenko of cynically obstructing his attempts at reform and supporting corrupt clans.
Saakashvili, who is widely credited with cracking down on corruption when he led Georgia from 2004 until 2013, was appointed Odessa governor in May 2015 in a surprise move by Mr Poroshenko.
Mr Saakashvili has since repeatedly accused the Kiev leadership of lacking a real commitment to reform. His political allies said this had made him a target of political infighting.
“I can’t stand this, I’ve had enough. I’m tired of this. And I want to say: nobody in my life has lied so much or so cynically to me,” Mr Saakashvili said, apparently in reference to Mr Poroshenko and the central authorities.
Vowing to continue to fight corruption, which he said went to the very top of Ukraine’s establishment, he told reporters: “I have decided to tender my resignation and start a new stage of the fight. I am not giving up.”
In another rebuke of the president, he said: “In reality, in Odessa region, the president personally supports two clans.”
Mr Poroshenko’s office issued a statement saying he would accept Mr Saakashvili’s resignation if submitted by the cabinet.
“The issue of why Mr Saakashvili filed his resignation will be reviewed in an appropriate manner,” it said, without making any further comment on the former Georgian leader’s remarks.
Speaking alongside Odessa customs chief Yulia Marushevska, Mr Saakashvili said the work of reform-minded public officials in Ukraine had been thwarted by higher authorities who were interested in preserving the status quo.
Fellow Georgian Davit Sakvarelidze, who was fired from his post as a senior prosecutor for Ukraine in March, said Mr Saakashvili’s outspokenness had guaranteed his departure.
“All local clans are mixed together and work as one. It became impossible to act against them.
“Mr Saakashvili will not leave Ukraine and will be active politically. You’ll find out about this soon,” Mr Sakvarelidze was quoted as saying by website Gordon.
Opposition to Russia
Mr Saakashvili, a bitter opponent of Russia, was among several foreign politicians and technocrats to be given key posts by the pro-Western leadership in Kiev, after the Moscow-backed president Viktor Yanukovich fled in the face of mass street protests.
They were brought in as part of a drive to eliminate entrenched corruption and improve transparency in a country riven by cronyism, economic mismanagement and a separatist war in eastern Ukraine.
Since then, many have resigned or been dismissed.
In February, economy minister Aivaras Abromavicius, a Lithuanian, stepped down, saying vested interests were blocking his ministry's work.
Later, a government shake-up booted US-born finance minister Natalia Yaresko and Western-backed prime minister Arseny Yatseniuk out of office.
The appointment of Poroshenko ally Volodymyr Groysman as prime minister was seen as a move by the president to consolidate power.
Pro-European politician and activist Serhiy Leshchenko said Mr Saakashvili’s resignation illustrated an anti-reformist trend in the country.
“It is part of a broader development happening in Ukraine - an attack on anti-corruption fighters and people who back reforms,” he said.
Others thought Mr Saakashvili’s accusations should be taken with a pinch of salt.
"Knowing him, he tends to exaggerate," said Ukraine's former health minister Alexander Kvitashvili, another Georgian who has tendered his resignation, citing corruption.
“All of us have resigned at some point here. I don’t think it’s necessarily helpful when you come out with statements like that.
“Yes, maybe he didn’t get the support he needed, but the situation is very complicated and nothing’s black-and-white,” he told Reuters.