Number of Russian spies in the UK back to Cold War levels, say security services In the same year, Britain was accused of placing a fake rock containing a transmitter in a Russian street to help steal classified data. The UK initially denied any knowledge of the "spy rock" but earlier this year Jonathan Powell, Tony Blair's former chief of staff, admitted it was true. And last year allegations that Katia Zatuliveter, who had an affair with an MP on the defence select committee, was a spy were raised during an immigration tribunal. The panel concluded she was not a spy even though MI5 had "ample grounds for suspicion." It is believed there could be as many as 40 Russian spies active in the UK at any one time - similar to if not higher than numbers just before the end of the Cold War, sources said. In 2007, Jonathan Evans, the director general of MI5, said despite the thawing in tensions after the Cold War, he was still "expending resources to defend the UK against unreconstructed attempts by Russia, China and others, to spy on us." "It is a matter of some disappointment to me that I still have to devote significant amounts of equipment, money and staff to countering this threat," he said. They are resources which I would far rather devote to countering the threat from international terrorism - a threat to the whole international community, not just the UK. Oleg Gordievsky, a high profile KGB defector, has warned the number of spies here could be even greater than there were in the mid-1980s - when 39 intelligence officers were based in the embassy. Mr Gordievsky was a KGB colonel and head of station in London. He worked as a double agent for MI6 because his arrest in Russia in 1985 and subsequent escape to Britain. Jonathan Eyal, a Russia expert at the respected security think-tank, the Royal United Services Institute (Rusi), said: "They are back to where they were in quantity to the period just before the end of the Cold War." Mr Eyal said the UK is always of interest to Russia. It is seen as a potential back door in to US intelligence because a breach here could be like a "Trojan Horse" for breaching America's secret due to our close working relationship. The large number of oligarchs and high profile Russian figures and critics based here are also regularly monitored. Activities can range from general intelligence to obtaining information crucial to industry such as trade secrets or whether a company is ripe for take over, especially in the fuel supply industry. There are fears the level of spying will now step up this summer while intelligence officers concentrate on major events. Mr Eyal said: "It is likely there is going to be a dip in the capability of our security services in either identifying or monitoring increased activity because everything will be going in to the Olympics and Jubilee."