"Russian counterintelligence officers, in conjunction with their Ukrainian colleagues, will work to counter terrorism and extremism, and ensure the protection of secret information," the source said, adding that lists of FSB officers were being drawn up for approval by the Ukrainian side.
Ukrainian special services say they have not blacklisted any members of the FSB.
FSB officers were formerly stationed at the naval base but were ordered to leave in late 2009 by former Ukrainian President Viktor Yushchenko amid poor relations between the two countries.
On May 19, Russia and Ukraine signed an agreement to return FSB officers to the Black Sea Fleet facilities in Ukraine.
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