Skripal was spotted by the MI6 in Spain, where he was serving as Russia's military attache and later was recruited by the UK intelligence in 1995, providing valuable information about Russian intelligence service and the military objects, The Times said.
After Skripal left GRU in 2000, he continued to work for MI6, meeting with the secret service's agents in Spain and receiving about $5,000 for each meeting, according to the newspaper.
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In 2006, Skripal was sentenced in Russia to 13 years in prison for cooperating with MI6 and transferring names of Russian intelligence agents working undercover in Europe. In 2010, then Russian President Dmitry Medvedev signed a decree pardoning Skripal, with the latter then moving to the United Kingdom.
On Monday, UK police said that a man and a woman, who were later confirmed to be Skripal and his daughter Yulia, were found unconscious on a bench at a shopping center in Salisbury. Both of them were "in critical condition" and were being treated for suspected exposure to a nerve agent.
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Russian presidential spokesman Dmitry Peskov said that the Kremlin had no information on what could have caused the incident and noted that Moscow was open for cooperation. He refused to comment on media speculations about Russia's alleged involvement, noting that "we did not have to wait long" for these accusations.
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Meanwhile, a cemetery in the UK town of Salisbury is closed as part of the investigation into the poisoning of Russian former intelligence officer Sergei Skripal, local police said on Saturday.
We're sorry to say that the cemetery on London Road, Salisbury will remain closed to members of the public for now as we continue our investigations.— Wiltshire Police (@wiltshirepolice) March 10, 2018
Many apologies to anyone wishing to visit it tomorrow for Mothering Sunday. https://t.co/Y3irDiQqVv pic.twitter.com/DIKRlkSpAJ
At the same time, UK Defense Secretary Gavin Williamson said that the country’s forces were helping the authorities of Salisbury to evacuate the cars and other contaminated objects.
"Currently we're seeing our Armed Forces supporting the police in the ongoing investigations, making sure that contaminated vehicles have been removed from Salisbury safely and keeping the local population safe," Williamson said.