Stephen Kinnock, the director of the council's office in St. Petersburg, was detained Tuesday night for an hour until consular officials arrived to free him, The Times of London reported.

Then, the Federal Security Service, the successor agency to the KGB, called in Russian employees from the St. Petersburg and Yekaterinburg council offices or visited them at home, the Daily Telegraph reported.

Each country filed diplomatic protests with one another, with Russia demanding to know why the council had defied orders to close its offices by Jan. 1.

The Russian government has repeatedly claimed the council, which promotes the teaching of English and associated culture, is a front for intelligence-gathering.

Tensions between the two countries arose last year when Britain expelled four Russian diplomats in retaliation for the Kremlin's refusal to extradite Andrei Lugovoi, a former KGB officer and chief suspect in the 2006 London slaying of Russian dissident Alexander Litvinenko.