LONDON, March 5 (Reuters) - Former Russian military intelligence officer Sergei Skripal, who was convicted in 2006 of spying for Britain, is critically ill after exposure to unidentified substance in Britain, a source close to the investigation told Reuters.
Skripal, who Russia said betrayed its agents to British intelligence, was swapped for Russian spies caught in the United States as part of a Cold War style exchange in Vienna in 2010.
It was unclear what substance caused Skripal to fall ill, the source, who spoke on condition of anonymity, said.
Police said a man in his 60s and a woman in her 30s were found unconscious in Wiltshire but did not give their names. They are both in intensive care. (Reporting by Guy Faulconbridge, editing by Andy Bruce)