Moscow city skyline (Picture: PA).
Russia's deputy foreign minister has downplayed the idea of a prisoner swap involving an ex-US marine being held on Moscow on suspicion of spying.
Paul Whelan, who is a dual American and British citizen, was detained in late December.
His arrest led to speculation that Russia could be using him in exchange for Maria Butina, the Russian who pleaded guilty last month to acting as a foreign agent in the US.
But on Saturday, Russian news agencies quoted the nation's deputy foreign minister Sergei Ryabkov as saying it is too early to talk of "the possibility of exchanges" as Mr Whelan is yet to be formally charged.
In an interview with Sky News, Foreign Secretary Jeremy Hunt had warned Russia to not use UK citizens as pawns in "diplomatic chess games" after the arrest.
Mr Hunt said Mr Whelan, a 48-year-old who lives in Michigan but is a dual British national through his parents, was being given "every support that we can".
Mr Whelan was in Moscow to help plan the wedding of another former Marine because he had been to Russia several times before, according to his twin brother David.
On Thursday, the US Embassy in Moscow advised the British Embassy in Moscow that a US citizen detained by the Russian authorities also held British citizenship, and therefore requested consular assistance from the UK.
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."