Moscow , Russia ( CNN ) -- The British journalist expelled from Russia was denied entry when he came back to the country because `` he violated a number of rules concerning the work of foreign correspondents , '' the Russian Foreign Ministry said on its website Tuesday . Luke Harding , the Moscow reporter for the Guardian newspaper , was detained by Russian authorities , locked in a cell for 45 minutes , and then put on a plane back to London , according to an article in the Guardian Tuesday . He had been returning to Moscow after spending two months in London reporting on the U.S. diplomatic cables published by the website WikiLeaks . The British Foreign Office said the incident occurred on Saturday . Alan Rusbridger , the Guardian 's editor , said in a statement that Russia 's move was `` a very troubling development with serious implications for press freedom . '' But the Russian Foreign Ministry statement said the rules allegedly violated were set down in 1994 and are `` well known '' to all working journalists in the country . `` In particular , having applied for and received the extension of his accreditation at the end of November last year , Harding left Moscow for London for his own business without receiving a ( new ) foreign correspondent press card issued in his name , although he knew he should have done that . `` Therefore , if L. Harding is still interested in working in Russia during the validity term of his Russia visa , he needs to settle the issues related to his accreditation with the Russian Foreign Ministry Information and Press Department . `` If L. Harding complies with these rules , which are the same for all foreign correspondents , there will be no problems with his entry to the Russian Federation , '' the statement said . In a statement to Parliament , Britain 's Minister for Europe David Lidington made reference to the accreditation issue but not specifically the foreign correspondent press card . `` Indeed , last November the Guardian approached us for support to secure Mr. Harding 's reaccreditation as a journalist when his accreditation had been withdrawn . We made representations at a senior level and in the event , Mr. Harding was granted an extension of his accreditation as a journalist . '' Lidington said Harding had not been `` given any explanation for his exclusion '' and deplored any restrictions on free media and freedom of expression . `` We understand that Mr. Harding had previously been warned by the Russian authorities about several alleged violations of his status as a journalist -- including visits without permission to border zones and classified areas , '' he said . Lidington said Harding `` knows Russia well and has , over the last four years , given readers of the Guardian genuine insight into that country . '' Assigned to Moscow since 2007 , Harding covered many events , including the 2008 war between Russia and Georgia and the twin suicide attacks on the Moscow metro system in 2010 . He also wrote a number of controversial articles , including one on the speculation surrounding the alleged secret wealth of Russia 's powerful prime minister , Vladimir Putin . Last year , Harding was reprimanded by Russian authorities for unauthorized travel to areas closed to journalists . `` It is worrying that the Russian government should now kick out reporters of whom they disapprove . Russia 's treatment of journalists -- both domestic and foreign -- is a cause of great concern , '' Rusbridger said . CNN 's Maxim Tkachenko contributed to this report .
NEW : Russia said Harding violated rules involving the work of correspondents . Luke Harding has covered major stories in Russia since 2007 . Russian authorities reprimanded Harding last year .