A former US marine detained in Russia on suspicion of spying is innocent and was attending a wedding in Moscow, his family has said.
Paul Whelan, 48, was arrested in Moscow on Friday 28 December "while carrying out an act of espionage", according to the country's FSB security service.
His family has denied the accusation amid the lack of a detailed legal complaint from the Russian Federation and little response to the situation from the US state department.
In a tweet from his twin brother David, his family explained: "Paul is a retired marine and was visiting Moscow to attend a wedding."
Their statement continued: "We noticed that he was not in communication on the 28th, which was very much out of character for him even when he was travelling.
"We learned of his arrest on Monday morning after his detention was picked up on newswires and have contacted congressional representatives, the US embassy, and the state department.
"We are deeply concerned for his safety and well-being. His innocence is undoubted and we trust that his rights will be respected."
My brother was detained by the Russian government on Friday as an alleged spy. While the law library + info focus will remain, you may see an increase in off-message topics until we get him safely home. pic.twitter.com/2HIF1UmS1b
— David Whelan (@davidpwhelan) January 1, 2019
The arrest comes at a low point in relations between many Western states and Russia following several spying controversies.
US authorities have accused Russia of interfering in the 2016 presidential election and earlier this month convicted Maria Butina of acting as an illegal foreign agent.
Prosecutors said she sought to develop ties with the Republican Party with the aim of influencing US foreign policy.
Russian agents were also accused of being behind the poisoning of former Russian double agent Sergei Skripal and his daughter in Salisbury earlier this year. Russia denied the claims.
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According to reported interviews with the family, Mr Whelan had repeatedly visited to Russia in the past.
He is currently employed as director of the corporate security team for an American car components supplier called BorgWarner.