The US has provided assurances to the high court in London in an attempt to prevent a last-ditch appeal by Julian Assange against extradition, but the WikiLeaks founder’s wife has dismissed them as “weasel words”. Last month, two judges deferred a decision on whether Assange, who is trying to avoid being prosecuted in the US on espionage charges relating to the publication of thousands of classified and diplomatic documents, could take his case to an appeal hearing. They granted him permission to appeal but only if the Biden administration was unable to provide the court with suitable assurances “that the applicant [Assange] is permitted to rely on the first amendment, that the applicant is not prejudiced at trial, including sentence, by reason of his nationality, that he is afforded the same first amendment [free speech] protections as a United States citizen, and that the death penalty is not imposed”. On Tuesday, details emerged of the assurances given by the US, which stated that he “will not be prejudiced by reason of his nationality with respect to which defences he may seek to raise at trial and at sentencing”. It referred specifically to him having “the ability to raise and seek to rely upon” the first amendment but also said that its applicability “is exclusively within the purview of the US courts”. The assurances also state: “A sentence of death will neither be sought nor imposed on Assange.” If Assange is denied permission to appeal, he faces being extradited to the US within days as he will have exhausted all of his legal avenues in the UK courts. His only hope would then be if the European court of human rights intervened. Stella Assange, his wife, tweeted: “The United States has issued a non-assurance in relation to the first amendment, and a standard assurance in relation to the death penalty. “It makes no undertaking to withdraw the prosecution’s previous assertion that Julian has no first amendment rights because he is not a US citizen. Instead, the US has limited itself to blatant weasel words claiming that Julian can ‘seek to raise’ the first amendment if extradited. “The diplomatic note does nothing to relieve our family’s extreme distress about his future – his grim expectation of spending the rest of his life in isolation in US prison for publishing award-winning journalism. The Biden administration must drop this dangerous prosecution before it is too late.” The sides will argue over the worth of the assurances at a further high court hearing scheduled for 20 May. However, Assange’s lawyers have previously described US assurances given in other cases as “not worth the paper they’re written on”, echoing similar criticism from human rights group Amnesty International. Only last week, when Joe Biden said he was considering a request from Australia to drop charges against the WikiLeaks founder, Stella Assange said it was a “good sign”. There was no immediate comment from the US Department of Justice.