The 50-year-old activist is wanted for trial in America over the mass leak of military cables in 2010 and 2011, but a judge in January blocked the transfer over fears that Assange would take his own life in the “oppressive” US prison system.
Assange’s supporters on Wednesday morning revealed that the High Court has granted the US permission to appeal against that ruling, made by District Judge Vanessa Baraitser.
They suggested permission to appeal has been granted “on a limited basis”, at a future court hearing, on a date yet to be set.
Assange is currently being detained at HMP Belmarsh until the outcome of the appeal is known, while his supporters have repeatedly called for his immediate release.
Assange’s fiancee, Stella Moris, called the case against him “entirely baseless and abusive”, suggesting President Joe Biden should put an end to attempts to bring a prosecution.
"I am appealing directly to the Biden government to do the right thing, even at this late stage”, she said.
“This case should not be dragged out for a moment longer. End this prosecution, protect free speech and let Julian come home to his family.”
Assange spent almost seven years living in the Ecuadorian embassy in Knightsbridge, claiming political asylum. He has now been at Belmarsh for more than two years.