Ukrainian authorities pledged to clean up law-enforcement agencies after President Volodymyr Zelenskiy removed the nation's security chief and suspended its top prosecutor.

The head of the State Security Service Ivan Bakanov, a childhood friend of Zelenskiy whose appointment in 2019 was criticized over his lack of experience, was removed from his post amid questions over how Russian forces managed to take to the southern region of Kherson. Iryna Venediktova, installed as prosecutor general in 2020, is also a longtime Zelenskiy ally, who was a lawmaker on his party list.

Ukraine continues to identify people who "work for the enemy, who leak information to the enemy in the sixth month of the war," Andriy Smyrnov, deputy chief of Zelenskiy's staff, said Monday in televised comments.

As of today, 651 criminal proceedings have been registered for treason and collaboration by employees of the prosecutor's office, pretrial investigation bodies, and other law enforcement agencies, Zelenskiy said late Sunday in a daily address to the nation.

"More than 60 employees of the prosecutor's office and the Security Service of Ukraine have remained in occupied territory and are working against our state," Zelenskiy said. "Such an array of crimes against the foundations of the state's national security and the connections identified between employees of Ukraine's security forces and the secret services of Russia pose very serious questions."

Smyrnov said the president expected "more concrete results of work to clean up the agencies" and there will be investigations into the actions of both Venediktova and Bakanov. Based on the results, the president may ask parliament to dismiss them.