Oleg Gordievsky was the highest ranking spy to defect
Oleg Gordievsky is smuggled to Finland by British agents and becomes the highest-ranking KGB officer to defect to Britain.
The USSR expels 25 British nationals in a tit-for-tat spy row, two days after the UK government orders the expulsion of 25 alleged Soviet spies.
Vasily Mitrokhin, a KGB officer, defects to the UK after the USSR's collapse.
Moscow expels nine British diplomats, alleging they are part of a spy ring.
London expels four Russian diplomats.
Mr Berezovsky recently said he was warned of a murder plot
UK refuses to extradite Russian oligarch Boris Berezovsky.
The UK refuses to extradite ex-prime minister of the unrecognised Chechen Republic of Ichkeria, Ahmed Zakaev.
Russia's state security service, the FSB, accuses British diplomats of spying in Moscow with the help of hi-tech electronic equipment disguised as rocks.
Former KGB officer Alexander Litvinenko died of poisoning
Former KGB officer Alexander Litvinenko dies in London.
Boris Berezovsky tells the press that Andrei Lugovoi was responsible for the death of Mr Litvinenko.
Russia formally renews its demand for the extradition of Boris Berezovsky from Britain following a newspaper interview where he refers to overthrowing the Russian government.
Russia officially refuses a UK extradition request for Mr Lugovoi.
16 July, 2007
David Miliband announced the expulsions to Parliament
The UK government announces it is to expel four diplomats from the Russian embassy in London after Moscow's refusal.
17 July, 2007
Moscow warns the UK to expect "serious consequences" following the expulsion of its diplomats.
18 July, 2007
Russian billionaire Boris Berezovsky claims UK intelligence officers warned him a Russian hit man was going to kill him.
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