Russia has protested over the closure of the London bank account of the country's main state-run news agency.
The Russian Foreign Ministry claimed the closure last week of Rossiya Segodnya's account with Barclays was linked to Western sanctions over the crisis in Ukraine.
Rossiya Segodnya's general director Dmitry Kiselyov was on a list of key Russian politicians and officials subjected to European Union asset freezes and travel bans last year in response to Moscow's annexation of Crimea and destabilisation of eastern Ukraine.
In a statement, the Russian Foreign Ministry said it was demanding an explanation from the UK authorities, adding: "This situation has caused an obstacle for the work of the largest Russian news agency in Britain."
Russia's ambassador in London, Alexander Yakovenko, said on Twitter that the action amounted to "an example of censorship against alternative media".
The Foreign Office, Treasury and Barclays all declined to comment on the claims.