The two high-ranking officials -- Prosecutor General Iryna Venediktova and State Security Service (SBU) head Ivan Bakanov, a long-time associate of the President -- are now subject to an investigation and have been temporarily replaced.

"For a long enough time, we have been waiting for more concrete and sufficiently radical results from the leaders of these two departments, to clean these two departments of collaborators and state traitors," the deputy head of the Office of the President of Ukraine, Andrii Smyrnov, told Ukrainian television on Monday.

"However, in the sixth month of the war, we continue to find ... packs of these people, in each of these departments," Smyrnov said.

In his nightly video address on Sunday, Zelensky appeared to suggest that the pair had been fired. "Today I made a decision to remove the Prosecutor General from office and to dismiss the Head of the Security Service of Ukraine," Zelensky said, adding that many officials within both departments were suspected of treason.