UK counter-terrorism officers on Thursday started investigations to uncover the origin of the nerve agent used in the poisoning of former Russian spy Sergei Skripal and his daughter, Yulia, in Salisbury.
The police said government scientists had identified the nerve agent used, but would not make that information public at this stage.
The police were yet to say if they knew how and where the poison was administered, the BBC reported.
"Having established that a nerve agent is the cause of the symptoms... I can also confirm that we believe that the two people who became unwell were targeted specifically."
Hundreds of detectives, forensic officers, analysts and intelligence officers are working on the case, which has drawn comparison with the killing of Russian dissident Alexander Litvinenko with radioactive polonium-210 in London in 2006.
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