Tensions between Britain and Russia are deteriorating.
The friction has intensified because of the British investigation of the murder of former Russian KGB officer and dissident Alexander Litvinenko, who died in England last year after ingesting polonium-210. The attack on Litvinenko exposed other Britons to the radioactive substance.
Before his death, Litvinenko accused Russian President Vladmir Putin of being behind the death plot. British investigators have named former KGB officer Andrei Lugovoi as a supect in the case, but Russian authorities refuse to extradite him.