Anyone with any information should contact Det Sgt Alan Clements via the 24-hour Police Enquiry Centre on 101.
If you don't want to speak directly to the police, you can contact the independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org. No personal details are taken, information is not traced or recorded and you will not go to court.
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The Bishop of Salisbury has called the attack on Segei Skripal and his daughter Yulia "a violation of our community."