David King, who as the Government's Chief Scientist played a key role in the investigation into Litvinenko's murder, has accused the Russian president of masterminding the murder of nearly 300 of his own people in the Moscow apartment bombings in 1999, which Putin blamed on Chechen rebels.

"I can tell you that Putin was responsible for the bombings," Sir David claimed to Mandrake at the Morgan Stanley Great Britons Awards. "I've seen the evidence. There is no way that Putin would have won the election if it wasn't for the bombings. Before them he was getting 10 per cent approval ratings. After, they shot up to 80 per cent."