Wikileaks Founder Julian Assange shows signs of psychological torture after several years' worth of "progressively severe forms of cruel, inhuman or degrading treatment," the UN's torture expert Nils Melzer said.

The UN's special rapporteur on torture said Assange had been deliberately exposed to "cruel, inhuman or degrading treatment or punishment" for years as he lived in London's Ecuadorian embassy.

He said that Assange could have his human rights violated if he is extradited to the US and that he appealed the UK, where he is currently imprisoned, not to extradite him.

He accused the US, UK, Sweden, and Ecuador of "ganging up to deliberately isolate, demonize and abuse a single individual for such a long time and with so little regard for human dignity and the rule of law."

He also said that Assange does not have access to the resources he needs to defend himself as he faces spying accusations in the US and rape allegations in Sweden.

Wikileaks Founder Julian Assange shows the symptoms of psychological torture and could have his human rights violated if he is extradited to the US, a United Nations torture expert said in a scathing statement that accused countries of ganging up to demonize Assange.

Nils Melzer, the UN's special rapporteur on torture and other cruel, inhuman or degrading treatment or punishment, said that he examined Assange alongside two medical experts in early May and found that Assange was displaying "extreme stress, chronic anxiety and intense psychological trauma" after being subjected to several years' worth of "progressively severe forms of cruel, inhuman or degrading treatment."

Assange is currently on his seventh week of a 50-week sentence in the UK's Belmarsh prison after he was expelled from Ecuador's London embassy.

Julian Assange is arrested at London's Ecuadorian Embassy in April. Screenshot/Sky News

He lived there for seven years and was arrested by British police for breaching bail conditions once Ecuador revoked his asylum in April.

Read more: Julian Assange has 'dramatically lost weight' since being imprisoned, and is so ill he can barely speak, WikiLeaks claims

Melzer said that Assange had been "deliberately exposed, for a period of several years, to progressively severe forms of cruel, inhuman or degrading treatment or punishment, the cumulative effects of which can only be described as psychological torture."

Assange also faces potential extradition to the US, where he has been accused of spying, and Sweden has reopened an investigation into rape allegations made against Assange, which he denies.

Melzer appealed to the British Government not to extradite Assange to the US "or to any other State failing to provide reliable guarantees against his onward transfer to the United States."

Read more: Julian Assange is being held in the UK's most notorious prison that was once known as 'Britain's Guantanamo Bay'

He said that his "urgent concern" is that "in the United States, Mr. Assange would be exposed to a real risk of serious violations of his human rights, including of his freedom of expression, his right to a fair trial, and the prohibition of torture and other cruel, inhuman or degrading treatment or punishment."

A police van outside the Ecuadorian embassy in London after Assange was arrested by British police. Peter Nicholls/Reuters

WikiLeaks said that Assange will get 175 years in jail if he is extradited to the US.

Melzer criticized the US, the UK, Sweden, and Ecuador for what he described as "ganging up" on Assange.

"In 20 years of work with victims of war, violence and political persecution I have never seen a group of democratic States ganging up to deliberately isolate, demonize and abuse a single individual for such a long time and with so little regard for human dignity and the rule of law."

"The collective persecution of Julian Assange must end here and now!"

Melzer said there had been a "relentless and unrestrained campaign of public mobbing, intimidation, and defamation against Mr. Assange, not only in the United States, but also in the United Kingdom, Sweden and, more recently, Ecuador."

UN special rapporteur on torture Nils Melzer in Turkey in 2016. ADEM ALTAN/AFP/Getty Images

He urged these governments to "take measures for the protection of his most fundamental human rights and dignity" and said they "have created an atmosphere of impunity encouraging Mr. Assange's uninhibited vilification and abuse."

A spokesman for the British government told The New York Times that the government nation supported Melzer's work and mandate, but did not agree with some of his observations and would issue a response. The Justice Department declined to comment to The Times, while Ecuadorean and Swedish officials could not be reached on Friday.

Melzer said that Assange has currently limited access to his legal representation and documents that would allow him to prepare his defense for these cases.

He also warned that Assange's extradition raises "serious concern over the criminalization of investigative journalism in violation of both the US Constitution and international human rights law."

Julian Assange after he was arrested by British police outside Westminster Magistrates Court in London. REUTERS/Peter Nicholls

WikiLeaks said this week that Assange already was in poor health from his seven-year stay in the Ecuadorian embassy and that seven weeks in prison had caused his condition to worsen.

It said Assange has "dramatically lost weight" and that his current mental state meant that it is "not possible to conduct a normal conversation with him."

Read more: Wikileaks says Julian Assange could face 175 years in prison after US files 17 new charges against him

Reuters reported that Assange was too ill to appear via video link at a hearing over whether or not he would be extradited.

The United Nations previously criticized Assange's 50-week sentence as "concerning" and disproportionate."

Assange's time in the Ecuadorian embassy was marked with Ecuador accusing him of spying and mistreating staff, as well as being deeply unhygienic.

Melzer said that over the last nine years "Assange has been exposed to persistent, progressively severe abuse ranging from systematic judicial persecution and arbitrary confinement in the Ecuadorian embassy, to his oppressive isolation, harassment and surveillance inside the embassy, and from deliberate collective ridicule, insults and humiliation, to open instigation of violence and even repeated calls for his assassination."