The Council's chief executive, Martin Davidson, said on Thursday that 10 employees had received late-night visits from Russian tax police, and that all the 20 staffers had been interviewed by Russian security officials.
"In St. Petersburg, the British Council implemented projects in culture and foreign relations. The projects have been frozen for the next three weeks," said Stanislav Smirnov, spokesman for the St. Petersburg office.
He said one of the projects, the British Animation Festival planned for February 14, may not take place.
Smirnov said about 20 people worked for the Council in St. Petersburg, including two British citizens, who were still in Russia. He declined to comment on the fate of the Russian employees.
The St. Petersburg office suspended work on Wednesday, and the Yekaterinburg office in the Urals closed temporarily the next day following Russian accusations of legal status irregularities and tax arrears, and amid growing tensions between the two countries.
The Moscow office of the British Council continues to operate.
British Ambassador in Moscow Tony Brenton and U.K. Foreign Secretary David Miliband have insisted the Council's operations in Russia were absolutely legitimate.
Russia's Foreign Ministry said Friday Britain's attempts to politicize the situation surrounding British Council would only serve to harm bilateral relations, and spokesman Mikhail Kamynin said London's decision to suspend the Council's regional offices had been long overdue.
"The decision to suspend the British Council's offices in St. Petersburg and Yekaterinburg is what the British side should have done long ago," he said.