A legal UN panel announced on Friday that controversy-ridden Wikileaks founder Julian Assange should be allowed to walk free and be compensated for his "deprivation of liberty".
Assange -- who faces extradition to Sweden over a rape claim, which he denies -- claimed asylum in London's Ecuadorean embassy in 2012.
Speaking at a news conference via a video link from the embassy, he said the opinion of the panel was "vindication".
"Today (Friday) that detention without charge has been found to be unlawful. I consider the outcome a vindication," he said.
Assange claimed there was no appeal against the panel's decision; it was a matter of "settled law", The Guardian reported.
He insisted the panel's findings were legally binding. The panel was a higher body than national law.
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Assange said that if Britain and Sweden continued to undermine the panel's finding they would be hit diplomatically.
"We have now a victory, and decided law on this case," he said.
Earlier in the day, the UN's Working Group on Arbitrary Detention insisted Assange's detention "should be brought to an end, that his physical integrity and freedom of movement be respected".
"Assange should be afforded the right to compensation," it added.
The 44-year-old Wikileaks founder has been subjected to "different forms of deprivation of liberty" initially while he was held in isolation at London's Wandsworth Prison for 10 days in 2010, the panel said.
However, a British Foreign Office spokesman said: "Julian Assange has never been arbitrarily detained by the UK."
The office said the report "changes nothing" and it will "formally contest the working group's opinion".
Foreign Secretary Philip Hammond said Assange was a "fugitive from justice", adding that he can come out "any time he chooses" but will still have to face justice in Sweden.
The Met Police said it will make "every effort" to arrest Assange should he leave the embassy.