Saakashvili lashed into Yatsenyuk's reform agenda during a September 3 television interview with Ukraine's Channel 5 network, saying government institutions were suffering from "paralysis" and accusing officials in Kiev of "sabotage" against his own reform efforts.
"Decisions about reforms are not being made," Saakashvili told the network owned by Ukrainian President Petro Poroshenko, who tapped the former Georgian leader to head the Odessa region in May.
"What the government is calling reforms, I can't call reforms."
Speaking in Russian, Saakashvili added that he had heard Yatsenyuk "call raising tariffs reforms."
"I don't call those reforms," he said.
"I call that the consequences of the economic crisis, the consequences of what is happening in the country. Tariffs indeed need to be raised. But this is not reform."
Yatsenyuk responded sharply at a September 4 cabinet meeting, describing Saakashvili's criticism as "deceitful accusations" that will only hamper Ukraine's reform efforts.
"I understand how difficult things are for him," Yatsenyuk said, according to an official transcript.
"They're difficult for everyone. We can all agree on this. For that reason, emotions and baseless accusations play into the hands of those who are against reforms in the country and those who are against real change in Ukraine."
Ukraine has long been beset by political infighting and ruthless jostling for power among its tycoons, a caste from which Poroshenko, a billionaire chocolate manufacturer, emerged to win last year's presidential election after ex-President Viktor Yanukovych fled the country amid mass unrest.
Tensions between Yatsenyuk and Poroshenko -- as well as other opponents of the previous regime -- have surfaced since the Euromaidan protests that helped oust Yanukovych, a Kremlin ally, in February 2014.
These fissures are widely seen as capable of derailing reforms and plunging the country into further political turmoil at a time when Ukraine continues to battle pro-Russian separatists in the east of the country despite a fragile cease-fire reached in Minsk in February.
Saakashvili, a longtime friend of Poroshenko's, is widely credited with conducting sweeping reforms in his native Georgia, including a harsh crackdown on drugs and government corruption.
He has appeared committed to launching similar efforts in Odessa, whose eponymous main city is a notorious hub for crime and drug trafficking and has come under additional pressure with the arrival of Ukrainians displaced by war to the east.
A recent petition posted on the Ukrainian president's newly launched online initiative to court voters' ideas proposed appointing Saakashvili to Yatsenyuk's post in order to speed reforms.
The petition had garnered 550 signatures as of September 4, well below the 25,000 required for consideration by the government.
In his interview with Poroshenko's Channel 5, Saakashvili suggested "central structures of authority" controlled by "oligarchs" in Kiev are organizing a campaign of "sabotage" against him.
"Authorities in Ukraine are controlled by oligarchic interests," Saakashvili said.
Saakashvili told RFE/RL's Russian Service in a September 4 interview that previous cadres of "corrupt" Ukrainian bureaucrats were now "playing dead" but "definitely are not dead."
"They undoubtedly will try to disrupt [anticorruption efforts]," Saakashvili said, adding that he and his team were trying to make Odessa an example for reforms across all Ukraine.
Yatsenyuk, meanwhile, criticized Saakashvili for personnel decisions and delays in presenting a plan for a road to be built to the Romanian border.
Calling Saakashvili by his first name, Yatsenyuk said the Odessa governor "should work" and "will work."
"I don't react to any personal attacks," Yatsenyuk said.
"This isn't about personalities or emotions. This is about responsibility for the fate of the country. About my responsibility before Ukraine. About Mikheil's responsibility before Odessites."
He added: "Any attempt to say, 'They didn't give it to me,' or, 'I wasn't able to,' this is not right. It's a sign of weakness. Strong people stand up and act. Let's do that together."
Source: Radio Free Europe