Valery Sharifulin/ITAR-TASS Photo/Corbis

Three and a half years after he sought temporary asylum in the Ecuadorean embassy in London only to find himself a captive instead, a UN group has ruled that UK and Swedish authorities unlawfully detained WikiLeaks founder Julian Assange in violation of their international human rights obligations.

The UN Working Group on Arbitrary Detention said in a statement released today that UK authorities should let Assange leave the embassy and that both the UK and Sweden should compensate him for what it said was an "arbitrary" or prohibited detention.

"Having concluded that there was a continuous deprivation of liberty, the Working Group ... found that the detention was arbitrary because he was held in isolation during the first stage of detention and because of the lack of diligence by the Swedish Prosecutor in its investigations, which resulted in the lengthy detention of Mr. Assange," the UN group wrote in its report. The group said that Sweden and the UK should "assess the situation of Mr. Assange to ensure his safety and physical integrity, to facilitate the exercise of his right to freedom of movement in an expedient manner, and to ensure the full enjoyment of his rights guaranteed by the international norms on detention." The group didn't elaborate on the nature of the compensation Assange should receive.

Although Assange has technically been a voluntary resident at the embassy since he sought asylum there in June 2012, he has effectively been a captive in that he has been forced to remain inside the building or risk arrest by UK police outside the embassy, even though he's never been charged with a crime.

The finding released today is not legally binding, and UK and Swedish authorities have indicated that they reject the UN body's conclusion. Both nations have said in statements that Assange has never been under detention and is free to leave the embassy, though the UK acknowledges that as long as the Swedish arrest warrant still stands, he will be arrested if he leaves.

“We have been consistently clear that Mr Assange has never been arbitrarily detained by the UK but is, in fact, voluntarily avoiding lawful arrest by choosing to remain in the Ecuadorian embassy," the British Foreign Office told the Guardian in a statement. "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 Mr Assange to Sweden."

Regardless of the finding's lack of legal strength, it adds fuel to the pressure already on Sweden to withdraw the arrest warrant for Assange, as his defense attorneys have demanded. It also weakens the ability of the UK and Sweden to apply pressure on other countries for human rights violations.

"I've been detained now without charge in this country, the United Kingdom, for five and a half years," Assange said over video feed at a news conference held by his lawyers at London's Frontline Club this morning, including the year and a half before he entered the embassy when he was briefly detained and then put on house arrest. "That’s five years where I’ve had great difficulty seeing my family and seeing my children."

The UN body's announcement today comes after lawyers for Assange filed an application for relief (.pdf) in 2014 calling his detention "harsh and disproportionate."

His lawyers argued that the detention was unlawful because it prevented Assange from exercising his right to asylum and because a Swedish prosecutor failed to conduct her investigation of him in a manner that was consistent with his rights. "She had an obligation to question him expeditiously, and it was her failure [to do this] that meant that the investigation ground to a halt [for more than five years]. That was a contributing factor to the length of the detention," Melinda Taylor, one of the lawyers representing Assange, told WIRED.

"Today that detention without charge has been found by the highest organization in the United Nations that has the jurisdiction of considering the rights of detained person to be unlawful," Assange said.

Assange has faced arrest for several years on two warrants, one issued in 2010 by Sweden and one issued in 2012 by UK authorities, which is related to the warrant from Sweden. If the two nations adhered to the finding today and cancelled the warrants, it would have allowed him to leave the embassy without threat of arrest by them. He would then have been able to proceed to Ecuador under that nation's protection if that's where he decided to pursue long-term asylum. But even if a path opened for him to leave the embassy, the investigation against him in Sweden has not been dropped.

He also still faces legal jeopardy in the US, where a 2010 grand jury investigation found that there was sufficient evidence to bring charges against him in relation to his publication of documents leaked to him in 2010 by Chelsea Manning. Although US authorities asserted in 2013 that no charges had actually been filed against Assange at that point, this could change, and at any time Assange could find himself facing a US arrest warrant.

The warrant out of Sweden was issued after authorities there demanded he travel to that country for questioning in relation to an investigation into alleged sex crimes. The investigation was launched after Assange had sexual relations with two women in Sweden. Assange has denied any criminal conduct and has insisted that his relations with the women were consensual. Police documents from the case, which were leaked online in 2011 indicate that the encounters were consensual at first, but that the women subsequently objected to some of Assange's actions, to no avail. They went to police only to get authorities to force him to take an HIV test and were surprised when prosecutors opened a rape investigation against Assange.

Although Assange has never been charged with any wrongdoing in the six years since the investigation began, his freedom has been effectively curtailed. Swedish authorities allowed Assange to leave Sweden that country in 2010, even though an investigation was underway, and only later sought his arrest, demanding he return for questioning—a demand he has been fighting ever since.

The second arrest warrant filed in the UK was for breach of bail, which occurred when he fled to the Ecuadorean embassy in June 2012 after losing his protracted legal battle to avoid extradition to Sweden for questioning. Assange had been out on bail while battling the extradition, and violated its terms when he failed to return to the country house where he was required to sleep at night. The penalty for violating bail is normally six months, Taylor noted to WIRED, which far exceeds the amount of time he has already been under detention in the embassy.

Assange has fought the extradition to Sweden because he and his attorneys suspect that the Swedish arrest warrant is a pretext to extradite him further to the US, where he fears he could face espionage charges for publishing – video and documents leaked to him by Chelsea Manning.

To avoid the risk of extradition to the US, Assange has long insisted that he would submit to an interrogation by Swedish authorities as long as they conducted it at Ecuadorean embassy or he was allowed to do it by video-link. But Swedish prosecutors insisted he travel to Sweden for questioning; they only reversed that stance recently. Last December, Ecuador and Swedish authorities reached a bilateral agreement for a Swedish prosecutor to travel to the UK to question Assange at the embassy. Those negotiations hit a snag, however, when someone requested that Ecuadorean officials be allowed to ask Assange the Swedish prosecutor's questions.

In the meantime, the investigation against Assange has been in limbo for nearly six years due to the intransigence of Swedish prosecutor Marianne Ny.

Assange’s attorneys argued during an appeal in Sweden in 2014 to dismiss the warrant that the investigation had "not been conducted with the effectiveness and urgency" it should have been. The Swedish court agreed, chastising Ny for her failure to examine alternative avenues for interrogation and thereby failing in her obligation "to move the preliminary investigation forward."

The head of the Swedish bar association even called the showdown a "circus" and urged the Swedish prosecutor to compromise. "It is time for this longstanding matter to be brought to a fair and proportionate end," Anne Ramberg, head of the bar association told the Guardian, at the time.

The Swedish prosecutor has already lost ground on her case due to the delays. Assange had initially been wanted for questioning in relation to four allegations sexual molestation charges, stemming from an encounter with one of the women. But the statute of limitations has since run out on that alleged crime, so only the rape allegation and investigation remains active.

"It is the end of the road for the legal arguments that have been presented today by Sweden and the UK," Assange said today. "Put simply, those arguments lost. There is no appeal. The time for appeal is over." He added: "It is now the task for Sweden and the United Kingdom…to implement the verdict."