Shortly after police confirmed on Wednesday that a couple in their 40s were critically ill after being exposed to the same nerve agent that almost killed former Russian spy Sergei Skripal and his daughter Yulia in March, the Russian embassy in the Netherlands tweeted a forceful denial of involvement.
"Pleased to confirm that the PC who sought precautionary medical advice at Salisbury District Hospital in connection with the incident in Amesbury has been assessed & given the all clear", local police said in a Tweet.
The police investigation into the poisoning of a couple in Wiltshire from a suspected nerve agent which almost killed a former Russian spy and his daughter is expected "to take months to complete", according to officers.
British officials blamed the March poisoning of Sergei and Yulia Skripal on Russian Federation.
The Conservative Council Leader of Salisbury described the man and woman exposed to Novichok as having a "chequered history with housing", as counter terrorism police lead the investigation.
They say that the current theory is that the British pair came into contact with nerve agent at a location not covered in Skripal decontamination sites.
But Wiltshire police say they are keeping an open mind about the cause of the pair's collapse, and it was not yet clear if a crime has been committed.
It was the same substance used to poison Russian double agent Sergei Skripal and his daughter Yulia. Paramedics were called back to the same address later that day, where a 45-year-old man, named locally as Charlie Rowley, had also fallen ill.
Britain has accused Russian Federation of poisoning the Skripals with Novichok - a nerve agent developed by the Soviet military during the Cold War - in what is the first known offensive use of such a chemical weapon on European soil since World War Two.
The spokesperson also added that there is nothing to suggest there is a risk to anyone else at the hospital or the wider public.
Nerve agents, including Novichok, can be inhaled as a fine powder, absorbed through the skin or ingested.
Officials have said the search underway Saturday could take weeks or months.
Wiltshire residents have been told to expect investigators in hazardous material suits to descend on the scenes, while other sites the couple were known to have visited before being taken ill are behind cordons.
Russian Federation has denied any involvement in either incident.
"The priority for the investigation team now is to establish how these two people have come into contact with this nerve agent", Basu said.