The British pair, a 44-year-old woman and a 45-year-old man, were hospitalised after being found unwell on Saturday in Amesbury, seven miles (11 km) north of Salisbury, where the Skripals were found slumped unconscious on a bench on March 4.
Police have been unable to locate the source of the contamination and have not ruled out the possibility of more people falling ill from coming into contact with the substance left over after the Skripals were targeted.
The Russian Embassy hit back, accusing the Government of trying to "muddy the waters" and 'frighten its own citizens'.
"The priority for the investigation team now is to establish how these two people have come into contact with this nerve agent", Basu said.
Moscow denied any involvement and suggested Britain had carried out the attack to stoke anti-Russian hysteria.
While agents of the Novichok class were highly lethal, the program was only partly successful, as some of the components were as toxic as the military-grade nerve agents and thus hard to handle safely.
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More than 42,000 Americans died from opioid overdoses in 2016, according to the latest numbers from the U.S. That figure includes 587 providers who were allegedly involved in "opioid diversion and abuse".
However, the Met police's senior counter-terrorism officer Neil Basu will later reveal that samples from both patients are sent to Porton Down laboratory for analysis on Monday.
Police say specialists have determined that a British couple in their 40s who visited the city of Salisbury were poisoned by the same lethal toxin - developed by the Soviet Union - that nearly killed Sergei and Yulia Skripal in the same English city in March.
"Meticulous and systematic searches are under way at a number of sites". They returned later in the day when Rowley also fell ill.
The man and woman poisoned on Wednesday are reportedly being treated at the same hospital where the Skripals were in intensive care months ago.
"He started feeling really hot and sweaty.so he went and had a shower, he was in his bedroom for a while and then he came out and felt a bit weird and started acting all amusing", said Hobson.
Officials have insisted that the risk to the wider public is low.
A friend of Rowley's said that he was a drug user and Sturgess lived in a hostel for homeless people in Salisbury. "Originally, we all thought it was the Russians, now it doesn't seem quite right", he said, noting that Sturgess and Rowley have no connection to Russia.
Police said there was no evidence that Ms Sturgess and Mr Rowley visited any of the sites that were decontaminated following the attempted murders of Sergei and Yulia Skripal.