(Xinhuanet) -- The sudden disappearance of a number of key witnesses in the Alexander Litvinenko investigation will make it even harder for British detectives, whose inquiry has now spread across five countries, The Times reported Wednesday. Scotland Yard was struggling to gain access to vital witnesses with former associates of Litvinenko, a former Russian spy, claiming that they were too scared to come forward. Interpol on Tuesday joined the investigation into the poisoning of Litvinenko, saying that it hoped to exchange information coming from Britain, France, Italy, Germany and Russia.
Russian officials have suggested that the poisoning may have been an attempt to discredit Moscow, The Times reported. The former agent had been arrested several times before fleeing to Britain with his wife and son in November 2000 and was granted asylum. He became a British citizen last month.