The man was picked up at Barcelona airport on Friday "by officers of the police technological investigation unit following an international complaint" a Spanish police spokesperson told AFP adding that he had later been transferred to Madrid.
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The detained man's wife, Maria Levachova, told the television channel Russia Today that her husband was held "at the request of the American authorities in connection with cyber crime".
The channel quoted Levachova saying that Spanish police told her "a virus which appears to have been created by my husband is linked to the victory of US President Trump" in the US election last November.
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Neither the Spanish police nor the Russian consulate confirmed the reason for the arrest when contacted by AFP.
Russia was accused by US intelligence and counter-espionage services of interfering in the US presidential election to boost Trump's prospects.
In mid-January, another Russian computer scientist wanted by the US, Stanislav Lisov, was arrested at Barcelona's El Prat airport.
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