March 6 (UPI) -- A former Russian agent convicted of spying and his daughter became critically ill after being exposed to an unknown substance in Britain, officials said.
Sergei Skripal, 66, and Yulia Skripal, 33, were spotted slumped on a bench at a shopping district Sunday, with Sergei Skripal making "strange hand movements."
The Skripals were taken to a hospital and are being treated for suspected exposure to an unknown substance. The former Russian spy and his daughter are in intensive care.
Two police officers involved in the incident are also being treated for minor injuries.
British police are investigating what substance the two may have been exposed to.
Kremlin spokesman Dmitry Peskov told reporters Tuesday that Russian authorities had no information on the incident.
"I cannot voice any response because we don't have any information," Peskov said.
"You know how he ended up in the West, what actions led to that, I will not repeat it. Now we can see that a tragic situation has happened but nevertheless, we have information about neither the reasons for it nor the activities the man was involved in."
British Foreign Secretary Boris Johnson said Britain would "respond appropriately and robustly" if it's found Russia is involved in poisoning Sergei Skripal and his daughter.
"It is too early to speculate," Johnson said. "But I know members will have their suspicions. If those suspicions prove to be well-founded then this government will take whatever measures we deem necessary to protect the lives of the people in this country, our values and our freedoms."
Skripal was granted refuge in 2010 during a spy swap alongside other Russian prisoners after being arrested in 2004 for spying for British intelligence to provide state secrets.