Julian Assange has warned the UK and Sweden of diplomatic repercussions if they do not abide by a UN panel's finding that he is the victim of arbitrary detention.
Assange said he felt a sense of "vindication" after the UN working group on arbitrary detention called on the UK and Sweden to end his "deprivation of liberty, respect his physical integrity and freedom of movement, and afford him the right to compensation".
Speaking via videolink from the Ecuadorian embassy at London's Frontline Club, Assange said he had been detained for five and half years.
"Today that detention without charge has been found by the highest organisation in the United Nations – that has the jurisdiction for considering the rights of detained people – to be unlawful," he said at a press conference attended by supporters and members of his legal team.
"I consider the outcome in this case to be vindication; the United Nations working group on arbitrary detention is the world expert body on understanding the law or when someone is to be detained or not detained."
However, UK foreign secretary Philip Hammond had called the UN panel's conclusion "ridiculous".
#Assange is a fugitive from justice, voluntarily hiding in the Ecuadorian embassy. I reject the report from #UNWGAD.
Assange, 44, is still wanted in Sweden for questioning in connection with an allegation of rape, and the Metropolitan police still intend on carrying out the European arrest warrant.
Sweden initially sought his extradition in 2010 over sexual assault allegations by two women, but last August inquiries into two counts of alleged sexual molestation and one count of unlawful coercion were dropped after the alleged offences reached their statute of limitations. The more serious allegation of rape is not due to expire until 2020, however.
Yesterday the Foreign and Commonwealth Office said the arrest warrant was still in place and that the UK had a "legal obligation to extradite" Assange, while the Metropolitan police said the Australian would be arrested if he left the embassy, despite a round-the-clock police presence having ended last October.
Assange said he considered Hammond's comments to be "beneath the stature that a foreign minister should express".
"This is a serious finding, it adds to an already important body of international law. While I understand the momentary political imperatives for foreign ministers of Sweden and the UK to look like they were correct in their earlier unlawful decisions the fact is they are not," he said. "There is a final decision. There is no ability to appeal the decision of the United Nations."
After claiming the UN panel's finding was the "end of the road" for legal arguments, Assange warned Sweden and the UK of the consequences of refusing to abide by the decision.
These included a global "weakening of human rights", both countries being treated less seriously on the international stage, and even the prospect of UN sanctions.
In concluding remarks he added: "Thank you, I miss my family, we have today a really significant victory that has brought a smile to my face and I hope many others as well."
He later appeared on a balcony of the Ecuadorian embassy to hail what he called a "victory that cannot be denied".
"What right does this government, the US government, or the Swedish government, have to deny my children their father for five and a half years without any charges in the country?" he said.
"My children are completely innocent parties to all that has happened. They are in the business of being children. It is time they had their father back."
The UN working group had earlier called on Assange to be allowed to walk free.
"The working group on arbitrary detention considers that the various forms of deprivation of liberty to which Julian Assange has been subjected constitute a form of arbitrary detention," said Seong-Phil Hong, who currently heads the expert panel.
"The working group maintains that the arbitrary detention of Mr Assange should be brought to an end, that his physical integrity and freedom of movement be respected, and that he should be entitled to an enforceable right to compensation," Hong added.
Assange had said he would leave the Ecuadorian embassy, where he has been since August 2012, on Friday if the UN panel rejected his case.
After the UN panel's findings were published, the UK government insisted: "This changes nothing."
A spokesperson said: "We completely reject any claim that Julian Assange is a victim of arbitrary detention. The UK has already made clear to the UN that we will formally contest the working group's opinion.
"Julian Assange has never been arbitrarily detained by the UK. The opinion of the UN working group ignores the facts and the well-recognised protections of the British legal system. He is, in fact, voluntarily avoiding lawful arrest by choosing to remain in the Ecuadorian embassy. An allegation of rape is still outstanding and a European arrest warrant in place, so the UK continues to have a legal obligation to extradite him to Sweden. As the UK is not a party to the Caracas Convention, we do not recognise 'diplomatic asylum'.
"We are deeply frustrated that this unacceptable situation is still being allowed to continue. Ecuador must engage with Sweden in good faith to bring it to an end. Americas minister Hugo Swire made this clear to the Ecuadorian ambassador in November, and we continue to raise the matter in Quito."
Anders Rönquist, director-general for legal affairs at the Swedish Foreign Ministry, echoed the UK, saying Assange was staying "voluntarily" at the embassy and was "free to leave ... at any point".
"Thus, he is not being deprived of his liberty there due to any decision or action taken by the Swedish authorities," he wrote in a letter to Hong.
Steve Peers, professor of EU law and human rights law at the University of Essex, told BuzzFeed News the working group's finding was unlikely to have any immediate impact.
"It's not binding, but legally speaking the European arrest warrant is," he said. "There's no easy way to get out of a European arrest warrant, as they are always backed by the European courts."
Peers said Assange could return to the UK courts challenging his extradition on the basis of the UN panel's conclusions, which could technically eventually reach the supreme court.
Alternatively, Assange could take his case to the UN Human Rights Committee, but as the UK does not allow people to do so, he would have to leave the embassy and appeal this way in Sweden, which does permit such appeals.
Lawyer, author and lecturer at UCL Philippe Sands said the panel's findings were "not the UN's finest day".
Have read the full WGAD #Assange report - poorly reasoned and unpersuasive. Not the UN’s finest day https://t.co/Wmq2YGHiBi
The working group's conclusion was not unanimous.
Of the five-strong panel, Ukraine's Vladimir Tochilovsky dissented, saying the finding "raises serious question as to the scope of the mandate of the working group".
"Mr Assange fled the bail in June 2012 and since then stays at the premises of the embassy using them as a safe haven to evade arrest," he wrote. "Indeed, fugitives are often self-confined within the places where they evade arrest and detention."