Police have said there is nothing to suggest that novichok is to blame for two people falling ill at a restaurant in Salisbury close to where Sergei and Yulia Skripal collapsed after being poisoned with the nerve agent.
On Sunday evening emergency services cordoned off part of the town after a man in his 40s and a woman in her 30s were taken ill in an Italian restaurant.
Wiltshire Police said they had been called to Prezzo by ambulance crews after a “medical incident” and had closed the restaurant and surrounding roads “as a precautionary measure”.
In the early hours of Monday, the force ended the “major incident status” and said both victims remained in hospital under observation.
“Due to recent events in the city and concerns that the pair had been exposed to an unknown substance, a highly precautionary approach was taken by all emergency services,” police said in a statement.
“Both were taken to Salisbury District Hospital and were clinically assessed. We can now confirm that there is nothing to suggest that Novichok is the substance.”
The statement continued: “At this stage it is not yet clear if a crime has been committed and enquiries remain ongoing. Salisbury District Hospital remains open as usual.
“A cordon will remain in place around Prezzo at this time as part of ongoing routine enquiries. All other areas that were cordoned off will now be reopened.”
A witness earlier claimed the pair were showing “the same symptoms” as the Skripals, who were poisoned by suspected Russian state assassins in March.
Amanda Worne tweeted: “Feeling a little apprehensive as Salisbury leaps to action again when 2 Russians are taken ill in Prezzos showing the same symptoms as before... AND WE WERE SITTING NEXT TO THEM! Now under police supervision waiting for medical team to give us the all clear!”
Ms Worne also wrote on Facebook of being caught up in “a major incident” after the pair sat near to her were taken “seriously ill”.
“We are being taken to a safe place and may need blood tests at Salisbury hospital,” she added.
South Western Ambulance Service said it was called to the restaurant at 5.38pm and dispatched four ambulances including a hazardous area response team.
The patients were conscious and were being treated at the scene, a spokeswoman added.
A source briefed by the emergency services said medics alerted the police because the symptoms “seemed consistent with novichok poisoning”. However, the source stressed those symptoms could be caused by other reasons.
“The symptoms of novichok poisoning and particular types of narcotic abuse are very similar,” they added.
A witness who was in Prezzo at the time said one of those taken ill was a blonde woman. The man who the woman had been dining with was found having a fit in the toilet, the witness said.
“When she came back she was hysterical. She called paramedics and the next thing an ambulance turns up and they come rushing in,” they added.
A source told Sky News that one of the two taken ill was Russian.
Police cordoned off around the restaurant, on the corner of Salisbury High Street and pictures posted on social media showed a hazardous material suit in the area, while a police officer was seen in protective clothing with their face covered.
Public Health England was informed of the incident and firefighters were also sent to the scene.
Witness Sam Proudfoot, 16, said he saw a person in a hazardous material suit go between the restaurant and the ambulance.
“I’ve been told two people were taken ill in there,” the student said.
“There’s a man in a full white body suit with a mask to his mouth going in and out of the back of the ambulance and the restaurant.”
Tensions in Salisbury remain heightened following the poisoning of the Skripals and the death of Dawn Sturgess, 44, who came into contact with novichok found in a perfume bottle dumped in the city’s Queen Elizabeth Gardens.
The Prezzo restaurant just a few hundred yards from the branch of the Italian restaurant chain Zizzi where the Skripals fell ill. Investigators later established nerve agent was smeared on the front-door handle of his the former spy’s home on 4 March.
Salisbury city council leader Matthew Dean said “understandably people [were] concerned” about the “latest possible incident”, but cautioned there had been “a number of false alarms since the Skripal poisoning”.
“Rightly the emergency services start with a highly precautionary approach until they know otherwise,” he added.
The Kremlin has repeatedly denied any involvement in the poisoning of the Skripals or Ms Sturgess, whose partner was left critically ill after finding the perfume bottle in the park.
The UK government has alleged military intelligence officers going by the names Alexander Petrov and Ruslan Boshirov attempted to murder the former MI6 information.
The two men last week appeared on Russian TV denying the accusation and insisting they had been visiting Salisbury as tourists.
The Zizzi restaurant where the Skripals ate after being poisoned has been permanently closed.