Documents leaked by fugitive US intelligence analyst Edward Snowden show Britain spied on Argentina to monitor its efforts to win sovereignty over the Falkland Islands, Argentine media said Friday.

Britain, which defeated Argentina in a brief, bloody war over the South Atlantic islands in 1982, carried out "covert interception and intervention operations and other maneuvers" on Argentina from 2008 to 2011, reported news portal TN, citing documents obtained from Snowden.

A close ally of top Kremlin critic Alexei Navalny said on Wednesday he has been given political asylum in Britain after fleeing Russia over alleged political persecution.

Vladimir Ashurkov -- who was executive director of opposition leader Navalny's anti-corruption fund -- told Moscow's independent TV channel Dozhd that British authorities had approved a request he filed last year. 

Turkey has arrested nine British nationals on the Syrian border as they sought to illegally cross over from Turkey, the army said on Thursday.

"Nine people of British nationality were arrested on the border trying to enter Syria from Turkey," the army said in a statement on its website, adding that the arrests took place in the Hatay region of southern Turkey.

U.S. Secretary of State John Kerry and his British counterpart Philip Hammond Monday voiced fears over possible political interference in Nigeria's vote count, as the country awaited the results of weekend elections.

"We have seen no evidence of systemic manipulation of the process. But there are disturbing indications that the collation process -- where the votes are finally counted -- may be subject to deliberate political interference," the two diplomats said in a joint statement.

British Foreign Secretary Philip Hammond said late Sunday he believed a nuclear deal with Iran could be reached, but insisted it must put an atomic bomb "beyond reach."

"We are here because we believe a deal can be done," Hammond told reporters waiting in the rain outside a Lausanne hotel as he became the last of the foreign ministers to arrive for talks with world powers.

Marathon Iran nuclear talks headed Friday towards a critical weekend as Britain said its foreign minister would join his U.S., Iranian and French counterparts in racing the clock to pin down a deal.

"The negotiations are difficult. They've been difficult since the beginning and they still are," Iranian Foreign Minister Mohammad Javad Zarif told AFP on Friday after meeting in Switzerland with top U.S. diplomat John Kerry for about 90 minutes.

Failure to secure a deal with Iran could mean a nuclear arms race in the Middle East, Britain's foreign minister warned in comments released on Thursday.

"I remain clear that no deal is better than a bad deal. But we should also be clear-eyed about the alternative," Foreign Minister Philip Hammond said in a speech in London.

Argentina branded Britain's plans to beef up defenses in the Falklands a "provocation" and a pre-election stunt Wednesday.

On Tuesday, British Defense Secretary Michael Fallon said London would spend £180 million ($268 million) over 10 years to counter "continuous intimidation" from Argentina in the disputed South Atlantic islands, which the two countries went to war over in 1982.

David Cameron went on the offensive against the opposition in a rowdy House of Commons on Wednesday at his last Prime Minister's Questions session before May's knife-edge election in Britain.

Conservative leader Cameron dealt a blow to the main opposition Labor party by ruling out a tax rise and peppering his answers with cutting put-downs of its leader, Ed Miliband.

Russia has more claim to Crimea than Britain has to the Falkland Islands, a senior Russian lawmaker insisted Sunday as London again denounced Moscow's "illegal annexation" of the peninsula.

"Attention London: Crimea has far more reason to be in Russia than the Falklands have to be part of Great Britain," said Alexei Pushkov, head of the Russian parliament's foreign affairs committee on Twitter.