"We write to you as members of the UK Houses of Parliament to request that you end the extradition proceedings against Julian Assange," 38 UK lawmakers said in a letter to the US Attorney General, Merrick Garland published by WikiLeaks on social media.
A similar letter has been written and signed by 48 Australian members of parliament.
"If the extradition request is approved, Australians will witness the deportation of one of our citizens from one Aukus partner to another - our closest strategic ally with Mr Assange facing the prospect of spending the rest of his life in prison," the letter, published by WikiLeaks, read.
In December 2021, Assange suffered a stroke in Belmarsh Prison during a High Court appearance via video. In December 2022, Assange's wife Stella Morris voiced her concerns about his physical and mental health, since he was detained alongside prisoners charged with serious crimes.
April 11 marks four years since Assange was put in London's Belmarsh prison. He is currently attempting to appeal his extradition in the European Court of Human Rights.
WikiLeaks was founded by Assange on October 4, 2006, but rose to prominence in 2010, when it began to publish large-scale leaks of classified government information. This included leaked papers about US war crimes in Iraq and Afghanistan, which prompted the US authorities to prosecute Assange under the Espionage Act for crimes punishable by 175 years in prison.