Russia has expelled 10 Norwegian diplomats from the country’s Moscow embassy, declaring them “persona non grata” after Oslo accused 15 Russian officials of espionage and likewise ordered them to leave Norway.

The Russian Foreign Ministry said it summoned Norwegian envoy Robert Kvile on Wednesday to inform him of the decision, and that it “strongly protested” Norway’s move to expel Russian embassy staffers earlier this month.

“This hostile step further aggravated the situation in bilateral relations, which are already at a critically low level,” the ministry said in a statement, adding that Kvile was “handed a note declaring 10 representatives of the Norwegian Embassy in Moscow and the Office of the Defense Attache as … ‘persona non grata.’”

The ambassador was also informed that Moscow would take additional measures in response to the “unfriendly actions,” including new restrictions on “the hiring of locally recruited Russian citizens by Norwegian diplomatic missions.” The ministry did not immediately elaborate on what those restrictions would entail. 

Norway’s Foreign Ministry later acknowledged that 10 of its diplomats had “been declared unwanted” by Russia, and said this was “an act of revenge” for Norway's decision to expel more than a dozen Russian officials on April 13.

Oslo claimed that Russian officials were intelligence operatives working under the cover of their diplomatic roles, with Foreign Minister Anniken Huitfeldt declaring Norway would not allow its embassies to be used for “covert intelligence activities.” Officials did not provide any proof of the alleged espionage, only stating they had monitored the Russians “over time” and determined they were spies. At the time, the Kremlin said it was considering an “appropriate answer” to the diplomatic purge.

Earlier this week, Sweden also accused Russian embassy workers in Stockholm of spying, announcing that five staffers would be asked to leave the country. 

Oslo previously ordered three other Russian diplomats to leave Norway in April 2022, claiming they “conducted activities that are incompatible with their diplomatic status,” though did not offer further details. That decision came amid a spate of expulsions by European countries to protest Russia’s attack on Ukraine last year, among them Germany, Greece, France, Sweden and Denmark. In retaliation, Moscow has announced that it would take “reciprocal” actions and has since expelled several foreign diplomats, including more than 20 German officials earlier this week.