A police officer was tested for possible exposure to the nerve agent Novichok in connection with the poisoning of a couple in southwest England on Saturday but was given the all clear, the local force said.
"Pleased to confirm that the police officer who sought precautionary medical advice at Salisbury District Hospital in connection with the incident in Amesbury has been assessed & given the all-clear," Wiltshire Police said on Twitter.
A couple named locally as Dawn Sturgess, 44, and Charlie Rowley, 45, fell ill last weekend in the town of Amesbury, following what tests later confirmed was exposure to Novichok.
Amesbury is not far from the city of Salisbury where a former Russian spy, Sergei Skripal, and his daughter were poisoned by the same type of nerve agent in March.
The British government accused Russia of trying to kill the Skripals, a charge Moscow angrily denied, sparking an international crisis.
The British couple were exposed to the nerve agent after handling a contaminated item, police have said.
Ministers said this week that a link between the two cases is a main line of inquiry, and has asked Moscow to help provide answers about what has happened.
Several sites in both Amesbury and Salisbury have been cordoned off by emergency services.
Salisbury hospital said it had seen "a number of members of the public who have come to the hospital with health concerns since this incident started and none have required any treatment".
"We would like to reiterate the advice from Public Health England that the risk to the wider public remains low," it said.
Novichok is a military-grade nerve agent developed by the Soviet Union during the Cold War.
Around 100 counter-terrorism officers are helping in the investigation into the latest poisoning, which police said Friday could "take weeks and months to complete".
So far, there is no evidence that the British couple visited any of the sites involved in the Skripal case.
A police officer stands guard at a cordon near Rollestone Street in Salisbury, southern England