The United Kingdom is fighting the controversial decision. NBC's Duncan Golestani reports.
Updated at 6:33 p.m. ET: LONDON -- Britain said it would not allow Julian Assange safe passage to leave the country Thursday, hours after the WikiLeaks founder was granted asylum by Ecuador amid an escalating diplomatic crisis.
U.K. Foreign Minister William Hague said he was determined to see Assange extradited to Sweden to face sex assault claims but added there were no plans to storm Ecuador's London embassy, meaning the current standoff could last indefinitely.
"We will not allow Mr. Assange safe passage out of the United Kingdom nor is there any legal basis for us to do so," Hague said during a press conference. "The United Kingdom does not accept the principle of diplomatic asylum."
Britain earlier said it might revoke the diplomatic status of the embassy, where the Australian has been holed up since June 19 after he exhausted all appeals after a 17-month legal battle.
Assange, who incensed American government officials by publishing thousands of secret U.S. diplomatic cables and Iraq and Afghan war dispatches in 2010, is wanted for questioning in Sweden over assault and rape claims, which he denies.
Hague insisted that the U.K.'s actions had anything to do with Assange's or WikiLeak's work.
Facundo Arrizabalaga / EPA
Police officers arrest a supporter of Wikileaks founder Julian Assange on Thursday outside the Ecuadorean Embassy in London.
"It's important to understand that this is not about Mr. Assange's activities at WikiLeaks, or the attitude of the United States of America," he said. "He is wanted in Sweden to answer allegations of serious sexual offenses."
Britain's Foreign Secretary said WikiLeaks founder Julian Assange will not be granted safe passage out of the U.K. despite being granted diplomatic asylum by Ecuador. ITV's Chris Ship reports.
Ricardo Patino, the Ecuadorean foreign minister, earlier told a news conference in Quito it was upholding international law by granting asylum. He expressed fury at Britain’s earlier threat to arrest Assange, saying it was a direct challenge to the Ecuador’s sovereignty.
Martin Alipaz / EPA file
A composite file photo of Wikileaks founder Julian Assange, left, and Ecuadorean President Rafael Correa, right.
Patino said there was a risk Assange would be taken to the United States where he "would not have a fair trial, he could be judged by special or military courts, and it is not unlikely to believe he would be treated in a cruel and degrading way, that he would receive a life sentence or death penalty, with which his human rights would not be respected."
A version of Patino’s statement was posted online by Ecuador's foreign ministry (in Spanish).
Sweden immediately summoned Ecuador's ambassador in Stockholm. "We want to tell them that it's [unacceptable] that Ecuador is trying to stop the Swedish judicial process," foreign ministry spokesman Anders Jorle said.
Jorle also said Assange was wanted in Sweden to answer allegations of "serious sexual offenses." The extradition had nothing to do with the work of WikiLeaks or with a desire by U.S. authorities to try him for publishing diplomatic secrets, he added.
Assange's recognition as a political refugee by Ecuador's leftist government was a big symbolic victory for the ex-hacker, but it did little to answer the question: 'How will he ever leave the embassy?'
"We're at something of an impasse," extradition lawyer Rebecca Niblock said shortly after the news broke. "The U.K. government will arrest Julian Assange as soon as he sets foot outside theembassy but it's very hard as well to see the Ecuadorean government changing their position."
She said there was practically no precedent for the situation, invoking the case of a Hungarian cardinal Jozsef Mindszenty, who camped out at the U.S. Embassy in Budapest from 1956 to 1971. "One can't see Mr. Assange doing the same thing," she told BBC television. "One side will have to back down eventually."
Assange’s friend Vaughan Smith, whose country manor estate Assange stayed at while under house arrest, said Assange feels he is being "crucified."
“He genuinely believes that. I know him well. He's not a rapist. He stayed in my home with my family and none of us felt that there was anything improper about his behavior," Smith said, according to ITN.
Assange will give a statement in front of Ecuador's embassy in London on Sunday, a spokesman said on Thursday, although it was unclear if the WikiLeaks founder would risk arrest by appearing in person outside the building.
"Julian Assange will give a live statement in front of the Ecuadorian embassy, Sunday, 2 p.m. (9 a.m. EDT)," WikiLeaks said in a message on Twitter. "It will be his first public appearance since March."
WikiLeaks spokesman Kristinn Hrafnsson declined to elaborate and would not say if the appearance would be at an embassy window or on the pavement.
Outside the embassy on Thursday, protesters chanting slogans in support of Assange tussled with police.
A Reuters reporter saw at least three protesters being dragged away by police as the crowd shouted: "You are trying to start a war with Ecuador." About 20 officers were outside the embassy trying to push away the crowd of about 15 supporters.
'Colonial times are over'
London had warned Ecuador in writing earlier in the day that a 1987 British law permits it to revoke the diplomatic status of a building if the foreign power occupying it "ceases to use land for the purposes of its mission or exclusively for the purposes of a consular post."
Quito bristled at the threat.
"We want to be very clear, we're not a British colony. The colonial times are over," Patino said in an angry statement after a meeting with President Rafael Correa.
"The move announced in the official British statement, if it happens, would be interpreted by Ecuador as an unfriendly, hostile and intolerable act, as well as an attack on our sovereignty, which would force us to respond in the strongest diplomatic way," he told reporters.
Ecuador, whose government is part of a left-leaning bloc of nations in South America, called for meetings of regional foreign ministers and the hemispheric Organization of American States to rally support in its complaint against Britain.
British officials have said they will arrest him the moment he steps foot outside the embassy, but until Thursday they had not previously suggested publicly that they might strip the embassy of its diplomatic inviolability.
In a statement, WikiLeaks accused Britain of trying to bully Ecuador into denying Assange asylum.
"A threat of this nature is a hostile and extreme act, which is not proportionate to the circumstances, and an unprecedented assault on the rights of asylum seekers worldwide," it said Wednesday.
In Washington, U.S. State Department spokesperson Victoria Nuland refrained from commenting on Ecuador's decision to grant Assange asylum. "This is an issue between the Ecuadorans, the Brits, the Swedes," Nuland said. She added, "with regard to this particular issue, it is an issue among the countries involved and we're not planning to interject ourselves."
NBC News' staff, Reuters and The Associated Press contributed to this report.
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