Jeremy Hunt has warned Russia not to use UK citizens as pawns in “diplomatic chess games” after a former US Marine was arrested on spying charges.
The Foreign Secretary said that Paul Whelan, 48, who lives in Michigan but has joint UK-UK citizenship, was being given “every support that we can” after his status became clear.
It is feared Mr Whelan is being held to exert pressure on US authorities to release Maria Buttina, a Russian who has pleaded guilty to acting as an unregistered foreign agent. She is alleged to have served as a “back channel” between the Kremlin and senior US Republicans during the 2016 presidential election.
Speaking in Singapore during an official visit to Asia, Mr Hunt said that “individuals should not be used as pawns of diplomatic leverage”.
He said: “We are giving [Mr Whelan] every support that we can, but we don’t agree with individuals being used in diplomatic chess games.
“It is desperately worrying, not just for the individual, but their families and we are extremely worried about him and his family as we hear this news.”
Mr Whelan was arrested in Moscow last week, apparently on espionage charges.
His twin, David Whelan, said his brother’s “innocence is undoubted and we trust that his rights will be respected”.
The incident will further strain UK-Russia relations at a time when they are already at their lowest level in recent history, following the poison attack in Salisbury blamed on Russian agents, resulting in the death of a woman.
Mr Whelan is a retired US Marine who has British citizenship through his parents. He was in Moscow to help plan the wedding of another former Marine because he had been to Russia several times, his brother said.
The US Embassy in Moscow advised the British Embassy on Thursday that a US citizen detained on 28 December informed them he also holds British citizenship.
A Foreign Office spokesman in London said: “Our staff have requested consular access to a British man detained in Russia after receiving a request for assistance from him.”
Mr Whelan’s Russian lawyer, Vladimir Zherebenkov, said he had appealed to the court against the detention of his client and requested he was released on bail.
He said: “I have sent an appeal against Whelan’s detention. In my appeal I am asking to change my client’s measure of restraint from arrest to release on bail to the sum determined by the court.”
Mr Zherebenkov said Mr Whelan, who faces a jail term of up to 20 years if convicted, remained in good spirits.
The news comes as Mr Hunt reiterated his attempts to broker the release of British-Iranian charity worker Nazanin Zaghari-Ratcliffe, who has been held in Tehran since April 2016 convicted of spying.
She is part-way through a five-year jail term and maintains her innocence. Her husband, Richard Ratcliffe, revealed she intends to start a hunger strike on 14 January in response to be denied a medical examination for lumps in her breast.