Zelensky said he was firing Prosecutor General Iryna Venediktova and security chief Ivan Bakanov amid a high number of cases of suspected treason by Ukrainian law enforcement officials.
Ukrainian President Volodymyr Zelensky on Sunday sacked his chief prosecutor and the head of the country's security agency in the largest government shakeup since the start of Russia's invasion nearly five months ago.
Zelensky said he was firing Prosecutor General Iryna Venediktova and security chief Ivan Bakanov amid a high number of cases of suspected treason by Ukrainian law enforcement officials.
Citing many cases of treason in the two powerful organisations, he said more than 60 former employees were now working against Ukraine in Russian-occupied areas, BBC News reports.
"Today, I made the decision of relieving of their duties the prosecutor general and the head of Ukraine's security service," Zelensky said in his daily address to the nation."
Zelensky said over 650 cases of suspected treason and aiding and abetting Russia by Ukrainian security officials are currently being investigated, including 60 cases of officials who have remained in territories occupied by Russia and are working against Ukraine.
"Such a great number of crimes against the foundations of national security and the connections established between Ukrainian law enforcement officials and Russian special services pose very serious questions to the relevant leaders," Zelensky said.
"Each such question will be answered."
Venediktova had led Ukraine's investigation into alleged atrocities committed by invading Russian forces in the town of Bucha outside Kyiv, which caused international outrage.
The sacked officials, Ivan Bakanov and Iryna Venediktova, have not commented.
In a video address late on Sunday, Mr Zelensky said: "Such an array of crimes against the foundations of the national security of the state... pose very serious questions to the relevant heads [of the two organisations]."
"Each of these questions will receive a proper answer," the Ukrainian president added.
The sacking of SBU chief Ivan Bakanov, a childhood friend of Mr Zelensky, follows the high-profile arrest of a former SBU regional head in Crimea, annexed by Russia in 2014. Oleh Kulinych is suspected of treason.
"Everyone who together with him was part of a criminal group that worked in the interests of the Russian Federation will also be held accountable," Mr Zelensky said. "It is about the transfer of secret information to the enemy and other facts of co-operation with the Russian special services."
Senior intelligence officials based in Kherson have also been charged and Mr Zelensky suggested that further action would be taken against other SBU officers.
It has long been assumed Ukraine had a problem with Russian infiltration of its security services and in his speech Mr Zelensky sought to lay out the impact of repeated security breaches.
There have been reports for several weeks that Mr Zelensky wanted to replace Mr Bakanov after coming to blame him for failures in stopping the Russian advance in February.
The 47-year-old was picked to head the intelligence agency in 2019 after managing Mr Zelensky's insurgent campaign for the presidency. Opposition figures criticised the appointment, arguing that the former TV producer was unqualified to lead the SBU.
Ms Venediktova will be succeeded by her deputy, Oleksiy Symonenko, Mr Zelensky said. She took office in 2020 as Ukraine's first female law enforcement chief after Mr Zelensky fired her predecessor, accusing him of not producing results.
But he warned at the time that someone else would be hired if she could not produce results.
Earlier this month she told the BBC that her office was investigating some 21,000 war crimes and crimes of aggression allegedly committed by Russia since the start of its invasion.