Detectives investigating the Novichok attack in Salisbury have confirmed that traces of the nerve agent have been found in a blood sample taken from a second police officer.
The officer from Wiltshire Police, who does not wish to be identified, was involved in the response to the poisoning of Sergei and Yulia Skripal.
The officer is said to have showed signs of exposure to small amounts of Novichok at the time - they received immediate medical treatment and quickly went back to work.
In a statement on their website, Metropolitan Police said:
These forensic tests were carried out as part of what remains an ongoing investigation, which has been unprecedented in its complexity and scale and has involved thousands of exhibits. Officers continue to work closely with scientists and experts to meticulously and methodically review and examine the evidence available to us.
Sergei Skripal and his daughter, Yulia, became ill after coming into contact with the nerve agent Novichok in March 2018. Wiltshire Detective Sergeant Nick Bailey is also thought to have come into contact with the poison when he searched their home.
The higher levels of exposure to Novichok suffered by the Skripals and Detective Sergeant Nick Bailey led to them falling critically or seriously ill.
Dawn Sturgess and Charlie Rowley also suffered high levels of exposure to Novichok following the incident in Amesbury in June 2018. Dawn died some days later, whilst Charlie also became critically ill.
Police have now contacted others whose blood samples were taken at the time, to seek consent for further forensic analysis. They want to confirm whether there are traces of Novichok in these blood samples to forensically identify further victims of the attack.
Public health experts say there is no change to the overall public health risk, which remains low.