March 7 (UPI) -- A former Russian spy and his daughter were poisoned by a nerve agent at a British shopping district earlier this week, New Scotland Yard said.
The poisoning incident, which put Sergei Skripal, 66, and Yulia Skripal, 33, into intensive care, is being treated as a "major incident involving attempted murder" by the administration of the deadly nerve agent, police said.
"Scientific tests by Government experts have identified the specific nerve agent used which will help identify the source but at this stage in a fast-paced ongoing investigation we will not comment further," British police said in a statement.
The Metropolitan Police's Counter Terrorism network has taken over the investigation due to the unusual nature of the case, New Scotland Yard said. The incident, though, has not been declared terrorism.
Assistant Commissioner Mark Rowley, the head of Counter Terrorism Policing, said police would monitor the case with the country's public health agency.
Russian Foreign Ministry Spokeswoman Maria Zakharova said Wednesday that Moscow hadn't received "any official requests or proposals of a joint investigation" into the incident between Russia and Britain.
"The situation has not become clear yet but the usual theories have already gained momentum," Zakharova said, adding that "these fake news stories are aimed at complicating Russia-UK relations, it is impossible to see any other reason behind them."
"Did you see anything out of the ordinary? It may be that at the time, nothing appeared out of place or untoward but with what you now know, you remember something that might be of significance. Your memory of that afternoon and your movements alone could help us with missing pieces of the investigation," Rowley said. "The weather was poor that day so there were not as many people out and about. Every statement we can take is important."
Two police officers who responded to the incident were treated for minor symptoms, including itchy eyes and wheezing, before they were cleared medically. A third officer is still in the hospital in serious condition.
Tuesday, British Foreign Secretary Boris Johnson pledged that Britain would respond swiftly if it was found that the Russian government was involved in the poisoning.
Skripal was granted refuge in 2010 during a spy swap involving other Russian prisoners after being arrested in 2004 for spying for British intelligence to provide state secrets.