An initial analysis could not find any traces of the man's deadly venom, but with another method it was established that he had small amounts in the blood, Scotland Yard states. The man received medical treatment after the incident and was able to return to service shortly thereafter.

Another police officer, who also participated in the investigation in Salisbury last year, became seriously ill and was in hospital for over two weeks.

Britain accuses Russia of being behind the poisoning of Russian ex-agent and his daughter Julia Skripal. Russia has categorically denied the allegations.