iStock/Thinkstock(LONDON) — A former British spy is in critical condition after being exposed to an “unknown substance,” British media say.

Wiltshire Police temporary Assistant Chief Constable Craig Holden confirmed in a statement that a man and woman were found unconscious on a park bench in Salisbury, England, Sunday. Holden did not identify the couple.

“The pair, who we believe are known to each other, did not have any visible injuries and were taken to Salisbury District Hospital. They are currently being treated for suspected exposure to an unknown substance,” Holden said.

British media have identified the man involved as 66-year-old Russian national Sergei Skripal.

Skripal was convicted in 2006 on charges of spying for Britain and sentenced to 13 years in a labor camp by Moscow’s military court, but was later released in a 2010 U.S.-Russia spy swap.

Skripal later took up residence in the U.K.

The man and woman are both in critical condition, Holden said. He said they do not believe there is any threat to the public.

The British Home Office told ABC News that the incident was a police matter and that it would not comment.

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