Ecuador has granted Julian Assange citizenship in an effort to resolve a diplomatic deadlock that has kept the Wikileaks founder holed up in the Ecuadorian embassy in London for more than five years.

The South American nation's foreign minister Maria Fernanda Espinosa revealed Assange was naturalized in mid-December in order to give the asylum seeker “another layer of protection” from those seeking to take legal action against him.

Assange first sought refuge in the embassy in 2012 when the UK supreme court rejected his appeal against extradition to Sweden. Swedish authorities had ordered Assange to answer questions over four alleged sexual offences.

Prosecutors have since abandoned the inquiry, however Assange still faces a charge for breaching bail in the UK, which is punishable by up to a year in prison.

Earlier this week, the UK Foreign Office revealed it had denied Ecuador's request that Assange be granted diplomatic status, meaning Assange can be arrested if he leaves the embassy.

“The UK did not grant that request, nor are we in talks with Ecuador on this matter. Ecuador knows that the way to resolve this issue is for Julian Assange to leave the embassy to face justice,” the Foreign Office said.

Assange rose to prominence after Wikileaks revealed millions of secret files. These included classified communication between the United States State Department and its diplomats around the world, and footage of US airstrikes that led to the deaths of journalists and Iraqi civilians.

More recently, Assange released hacked documents from the US Democratic Party during the presidential race between Hillary Clinton and Donald Trump.

Former Ecuadorian president Rafael Correa granted Assange asylum in 2012, explaining that he feared Assange would suffer retaliation over the revelations and could end up being extradited to the US.

Assange's presence in the embassy has led to a political impasse between the UK and Ecuador.

“It has been up to our government to look for alternatives to resolve this inherited situation which has not progressed for years,” Espinosa said on Thursday.

She added that Ecuador is currently “in dialogue with the United Kingdom” and exploring “other solutions” to the Assange issue.