"There are officers of our service among the employees of the Foreign Ministry," Naryshkin told reporters.
The SVR chief noted they were only few of them, adding that the officers were providing security of Russian diplomatic missions.
"This is a dirty, cynical provocation from a well-known group of countries that form an atmosphere of Russophobia," Naryshkin said.
Earlier this week, over 25 countries, including the United States and EU member states, decided to expel Russian diplomats over Moscow's alleged involvement in the attack on former Russian intelligence officer Sergei Skripal and his daughter in the UK city of Salisbury.
As described by London, this has been the "biggest collective expulsion of Russian spies" in history, a claimed denounced by Moscow as groundless.
On March 4, Skripal and his daughter were found unconscious at a shopping center in Salisbury and are currently being treated for exposure to what UK experts believe to be the A234 nerve agent.