The British Council, a body that promotes British culture and which has branches in several Russian regions, said local staff had been called in by the Federal Security Service (FSB) domestic intelligence agency, the main successor to the Soviet-era KGB.
A foreign office spokesman in London said: "We are aware of the incident and investigating the circumstances. Any attempt to intimidate British Council staff in Russia is completely unacceptable.
Russia and Britain have been trading accusations after London earlier defied Moscow's demand to close British Council offices in two Russian regions.
The argument comes amid ongoing tensions following the death of ex-KGB agent Alexander Litvinenko, who died in London in November 2006 after being poisoned with a fatal dose of radioactive polonium 210.
Britain wants Russia to hand over Andrei Lugovoi, a Russian businessman, whom the UK suspects murdered Litvinenko.
David Miliband, the British foreign minister, said Yuri Fedotov, Russia's ambassador to the UK, had been told that the only losers from the "attack" on the council would be the Russian government's reputation and its people.
Russia says the council's two offices in the northern city of St Petersburg and the Urals city of Yekaterinburg are operating illegally, a charge London denies.
A British foreign office spokesman said: "It is clear that the British Council operates legally in Russia according to the relevant conventions and agreements and to the benefits of thousands of Russian citizens."
A British Council spokeswoman said it was deeply concerned by Russia's moves.
|A British Council spokeswoman said it was |
deeply concerned by Russia's moves [AFP]
She said: "Our Russian staff in St Petersburg and Yekaterinburg were summoned for interviews by the FSB at their headquarters yesterday and were visited at their homes by interior ministry officials.
"We are deeply concerned by both of these incidents. Our main concern is the safety and security of our Russian and UK staff."
The FSB said on Tuesday it would speak to the British Council's Russian staff to prevent them being used by Britain "in provocative games".
Meanwhile, the council said Stephen Kinnock, head of its operations in St Petersburg, was stopped by police late on Tuesday and given a ticket for a minor traffic violation.
Kinnock's father, Neil, is a former European commissioner and the current chair of the British Council worldwide.