Russian authorities have ordered a British diplomat in Moscow to leave the country within two weeks, accusing the person of espionage. 

“Moscow will not tolerate the activities of undeclared British intelligence officers on Russian territory,” Russia’s Foreign Ministry said in a statement published Thursday morning.

Britain’s charge d’affaires in Russia, Danae Dholakia, was summoned to the Foreign Ministry where she was issued with a warning. “It was stated that Russia will continue to implement a line of zero-compromise on this issue in accordance with our country’s national interests,” Moscow said.

The statement also cautioned London against any “escalation of the situation,” threatening a “decisive ‘mirror’ response.”

A video posted on the Russian Foreign Ministry’s Telegram channel showed a person who appeared to be Dholakia leaving the ministry building amid chants of “Britain is a terrorist country!” from a crowd of several dozen demonstrators holding signs.

The U.K. Foreign Office did not immediately respond to a request for comment.