Julian Assange was given a “disproportionate” sentence for a bail violation, the United Nations has said as it accused British authorities of breaching his human rights.

The WikiLeaks founder ​was handed a 50-week sentence earlier this week and is being held at Belmarsh Prison in southeast London. He is fighting an extradition request made by the US over an alleged hacking conspiracy.

The UN Working Group on Arbitrary Detention said it was deeply concerned about the “disproportionate” sentence and claimed that violating bail was only “a minor violation”.

“The working group is further concerned that Mr Assange has been detained since 11 April 2019 in Belmarsh Prison, a high-security prison, as if he were convicted for a serious criminal offence,” it said.

“This treatment appears to contravene the principles of necessity and proportionality envisaged by the human rights standards.”

Key moments for Julian Assange Show all 9 1 /9 Key moments for Julian Assange Key moments for Julian Assange The situation today Assange was arrested after Metropolitan Police officers were invited into the Ecuadorian embassy on April 11 2019. How did it come to this? Ruptly TV Key moments for Julian Assange The break Assange shows the front page of the Guardian on July 26 2010, the day that they broke the story of the thousands of military files leaked by WikiLeaks AFP/Getty Key moments for Julian Assange Wanted A warrant for Assange's arrest was issued in August 2010 for counts of rape and molestation in Sweden AFP/Getty Key moments for Julian Assange Ruling The UK's Supreme Court ruled in 2012 that Assange should be extradited to Sweden to face trial Getty Key moments for Julian Assange Sanctuary Following the ruling, Assange was given asylum by the Ecuadorian governement over fears that his human rights would be violated if he were extradited, he has since remained in the embassy in London Getty Key moments for Julian Assange A friend in Pam Friend Pamela Anderson delivers lunch to Assange at the embassy in October 2016. She has since spoken against his arrest Getty Key moments for Julian Assange Arbitrarily detained A UN panel found in 2016 that Assange had been arbitrarily detained and that he had not been able to claim his full right to asylum. It urged Sweden to withdraw the charges against him Getty Key moments for Julian Assange The cat ultimatum Last year, the Ecuadorian embassy threatened to revoke Assange's internet access unless he stopped making political statements online and started taking better care of James, his pet cat. Assange accused Ecuador of violating his rights Reuters Key moments for Julian Assange Arrest Assange was arrested on April 11 2019. Ecuador revoked his asylum status and invited the Metropolitan Police in to the embassy to arrest him. Reuters

The panel added: “It is worth recalling that the detention and the subsequent bail of Mr Assange in the UK were connected to preliminary investigations initiated in 2010 by a prosecutor in Sweden. It is equally worth noting that that prosecutor did not press any charges against Mr Assange and that, in 2017, after interviewing him in the Ecuadorian embassy in London, she discontinued investigations and brought an end to the case.”

The same panel of legal experts previously stated that Assange was arbitrarily detained in the Ecuadorian embassy and should have had his liberty restored.

Mr Assange lived inside the embassy for almost seven years before being dragged out by police officers last month.

Pro-Assange protesters outside Westminster Magistrates’ Court on Thursday (AP)

WikiLeaks has said Assange is now living in “appalling” conditions at the prison, spending 23 hours a day in his cell.

The activist told Westminster Magistrates’ Court that he does not consent to being extradited to the US.

Speaking via video link from Belmarsh prison at a 10-minute hearing, Assange said: “I do not wish to surrender myself for extradition for doing journalism that has won many awards and protected many people.”

US authorities have charged him with conspiracy to commit computer intrusion which carries a maximum penalty of five years.

Ben Brandon, the lawyer representing the US at the Westminster Magistrates’ Court hearing, said there were computer room chats showing real-time discussions between Chelsea Manning and Assange over cracking a password to gain access to classified US documents and the public release of the information.