Investigators identified the suspects by cross-checking surveillance footage with records of people who entered Britain at the time, the Press Association said, citing an unnamed source.
Both have recovered and are being held in a secret location for their safety, with the United Kingdom government pointing the finger at the Kremlin for the attempted assassination.
According to reports on the U.S. network CNN, they are thought to be members of the Russian military intelligence service who travelling under different identities.
Subsequently, two Britons fell ill after being exposed to Novichok.
Sturgess, 44, and partner Charlie Rowley, 45, collapsed on June 30.
They are trying to establish where the container, thought to be a bottle of perfume, originated from, and how Mr Rowley and Ms Sturgess first encountered it.
Britain blamed Russian Federation for the poisonings and identified the poison as Novichok, a deadly group of nerve agents developed by the Soviet military in the 1970s and 1980s.
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Senior coroner David Ridley opened the inquest Thursday, but said the cause of Dawn Sturgess' death won't be given until further tests are completed.
Police said in a statement late on July 13 that a small bottle was found in Rowley's residence in Amesbury, 15 kilometers north of Salisbury, and scientists had confirmed that it contained Novichok.
Investigators are working on the theory that Sturgess sprayed Novichok straight onto her skin, the PA source said.
Inquests are medical and legal hearings conducted in Britain in cases of unnatural, sudden or violent death.
Experts from the Organization for the Prohibition of Chemical Weapons (OPCW) were also asked to carry out an independent investigation. They do not apportion blame. "They [the investigators] are sure they [the suspects] are Russian".
More than 400 exhibits, samples and items have been recovered by police investigating the poisoning of the couple.
On Wednesday, police started a search of the Queen Elizabeth Gardens in Salisbury.
Commenting on the media claims, the Russian envoy said that official London remains silent on the issue, stressing that media reports often fail to find any confirmation.
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