In a file photo, Germany s Foreign Minister Annalena Baerbock speaks with the media as she arrives for a meeting of NATO foreign ministers at NATO headquarters in Brussels on April 4, 2023. AP
The Foreign Ministry said in a statement that "the activity of these people was not in line with their diplomatic status", adding it had been in contact with Russia in recent weeks about the matter.
Berlin had previously not provided a justification for the departure of the diplomats, a move that triggered the expulsion of some 20 German embassy staff in Moscow, which the ministry confirmed left on Monday.
"Unlike the members representing Russia in Germany, our colleagues have always concerned themselves with behaving in accordance to their diplomatic status," the ministry said.
A close economic partner with Russia before the military offensive in Ukraine, Germany has since moved away from Moscow, financially and militarily supporting Kyiv in the conflict.
Since the onset of the conflict in Ukraine, Russian espionage in Germany has grown at a rate rarely equalled in recent years, according to German security services.
In spring 2022, Germany already expelled some 40 Russian diplomats who Berlin believed to represent a threat to its security.
Last October, the head of German's cybersecurity agency, Arne Schoenbohm, was fired after news reports revealed his proximity to a cybersecurity consultancy believed to have contacts with Russian intelligence services.
A month later, a German reserve officer was handed a suspended prison sentence of a year and nine months for spying for Russia.