British newspaper says Russia expelled its reporter

LONDON (Reuters) - A British journalist has been expelled from Russia for reporting on WikiLeaks diplomatic cables that contained unflattering descriptions of Russia's leadership, Britain's Guardian newspaper said on Monday.

If confirmed, the move is the latest twist in the turbulent relationship between Britain and Russia, which in recent months have seen tit-for-tat diplomatic expulsions but also the signing of an ambitious joint energy exploration deal.

"Russia has expelled me from Moscow. Stopped at pass control, put in a locked cell and deported. No explanation given," Guardian Moscow correspondent Luke Harding wrote on micro-blogging site Twitter.

The Guardian said Harding had flown to Moscow at the weekend but was denied entry, held in a cell for 45 minutes and had his passport returned only after boarding a plane back to Britain.

His visa was annulled and the Guardian said a security official told him: "For you Russia is closed."

"This is clearly a very troubling development with serious implications for press freedom, and it is worrying that the Russian government should now kick out reporters of whom they disapprove," Guardian editor Alan Rusbridger said in a statement published on the newspaper's website.

Russian officials could not immediately be reached for comment.

Harding had reported on U.S. diplomatic cables, leaked by the WikiLeaks whistle-blowing organisation, describing Russia as a "virtual mafia state."

Britain's foreign office said Foreign Secretary William Hague had contacted the Russian ministry of foreign affairs.

"We have been in contact with the Russian ministry of foreign affairs, including through a call from the foreign secretary to seek clarity on this decision. We are awaiting a reply," a foreign office spokesman said.

Tension has persisted between Britain and Russia over the 2006 murder of Kremlin critic Alexander Litvinenko in Britain. Russia refuses to extradite a suspect in the case, and the issue has cast a long shadow over ties between the two countries.

In December, Britain said it had expelled a diplomat from Russia's embassy in London for espionage and that Russia had responded in kind. However, in January, British oil major BP Plc

signed an ambitious energy deal with Russia's state-controlled Rosneft.

(Reporting by Mohammed Abbas in London and Gleb Bryanski in Moscow: Editing by Michael Roddy)