"Their actions are contrary to the Vienna convention on diplomatic relations," the president's office said in a statement, according to Reuters.
The statement added that it would inform the Russian ambassador of the expulsions.
The decision was made at a meeting between Finnish President Sauli Niinisto and the country's ministerial committee on foreign and security policy.
Russia has faced widespread sanctions and expulsion of its diplomats from European countries after it attacked the Ukrainian territory in what it calls a "special military operation."
SKH/PR