London, Nov 7: It was only a few months ago that the UK had a serious diplomatic tussle with Russia over the latter's alleged poisoning of a former Russian spy and his daughter on the soil of England. The incident had seen a major rift with both sides expelling each other's diplomats and many other countries, including the US, backed it and blasted the Kremlin.

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However, it seems the reason to worry for the English is yet a thing of the past. Tens of thousands of Russians currently living in Britain are spies, a significant report endorsed by a former head of M16, the UK's foreign intelligence service, has warned.

The study from Henry Jackson Society think tank said that there were 75,000 informants in London - which is half the number of Russians (150,000) living in the UK capital - who are actively helping Russia's secret service, the telegraph.co.uk reported.

The study also cautioned about a huge rise in Russian case officials in the UK since 2010, with 200 officials handling about 500 agents.