Scotland Yard has confirmed a man was arrested on suspicion of conspiracy to murder over an alleged plot to kill Russian exile Boris Berezovsky.The man, who was arrested in central London on June 21, was handed over to immigration officials two days later.The police statement appears to back up claims made by Mr Berezovsky who said a Russian hitman had planned to shoot him in a room at the Hilton hotel, in London's Park Lane.Mr Berezovsky was a friend of ex-KGB spy Alexander Litvinenko who was murdered in London by assassins who gave him lethal dose of radiation poisoning.Mr Berezovsky's spokeswoman said: "Three weeks ago, he was informed by Scotland Yard of a plot to kill him. They advised him to leave the country and after a week he was told it was OK to return."The would-be assassin apparently planned to lure Mr Berezovsky to a meeting and had taken a child with him so he looked less suspicious. The paper said the security service and Scotland Yard anti-terrorism police seized the gunman before he could carry out his plan.Tension has been mounting between Britain and Russia over the November 2006 murder of Mr Litvinenko by radioactive poisoning allegedly following a meeting with another former spy, Andrei Lugovoi.Four Russian diplomats have been expelled after Moscow refused to hand over Lugovoi to Scotland Yard. Russia is planning on responding to the expulsions within the next two days.On Tuesday, Russian deputy foreign minister Alexander Grushko warned his country would deliver an "adequate" response to the UK action, but did not spell out what it would be.Mr Berezovsky is also a fierce critic of Russian president Vladimir Putin, as was Mr Litvinenko who died in a London hospital weeks after he was poisoned by the radioactive isotope Polonium-210.© Independent Television News Limited 2007. All rights reserved.