British Foreign Minister Jeremy Hunt said Friday he was "extremely worried" about former U.S. Marine Paul Whelan, a dual U.S.-British citizen who has been detained in Russia on espionage charges.
In an interview with Sky News, Hunt warned Russia that "individuals should not be used as pawns of diplomatic leverage" and that Britain is "giving him every support that we can."
The U.S. embassy disclosed Whelan's British citizenship to U.K. officials Thursday, according to Britain's Press Association. The disclosure came one day after U.S. Ambassador Jon Huntsman Jr. met with Whelan in a Moscow prison.
On Monday, Russian Federal Security Service (FSB) officials said the 48-year-old Whelan had been detained on Dec. 28 "while carrying out an act of espionage," and a criminal probe has been ordered.
The FSB provided no further details, but Russia's state-run TASS news agency said Whelan faces up to 20 years in prison if convicted.
Earlier this week, U.S. Secretary of State Mike Pompeo said the U.S. had asked Russia to explain why Whelan was arrested and would demand his detention if deemed inappropriate.
Whelan is employed as director of global security at BorgWarner, an American automotive parts supplier.
Whelan's family learned of his arrest only after it was reported by Russian state news outlets, prompting the family to contact congressional representatives and U.S. diplomats.
"We are deeply concerned for his safety and well-being," the family said. "His innocence is undoubted, and we trust that his rights will be respected."
Whelan's arrest coincides with several spy scandals that have exacerbated tensions between Russia and the West, including the poisoning of former double agent Sergei Skripal and his daughter in Britain.
News of Whelan's detention came less than 24 hours after Russian President Vladimir Putin issued a New Year's greeting to U.S. President Donald Trump in which he said Moscow is amenable to a continuing dialogue with Washington on a range of topics.
In 2016, Izvestia, a Kremlin-aligned news outlet, reported there were 13 U.S. citizens in Russian jails at the time. The Kremlin has not since published any details on other Americans currently in Russian detention.