Boris Johnson refused to comment on the case, which will begin this month – but surprised the Commons by agreeing the extradition treaty between the two countries is “unbalanced”.
On Mr Assange, who faces up to 175 years in a US jail if convicted, Mr Corbyn backed MPs on the Council of Europe who have warned the extradition “sets a dangerous precedent for journalists”.
The one-sided arrangements would be “laid bare” when the courts decide whether he should be sent to the US on “charges of espionage for exposure of war crimes, the murder of civilians and large-scale corruption”, he said.
“Will the prime minister agree with the parliamentary report that’s going to the Council of Europe that this extradition should be opposed and the rights of journalists and whistleblowers upheld for the good of all of us,” Mr Corbyn demanded.
In response, the prime minister said: “I’m not going to mention any individual cases but it’s obvious that the rights of journalists and whistleblowers should be upheld and this government will continue to do that.”
Mr Assange, who is being held in London’s Belmarsh prison, has been indicted on 18 charges – 17 under the Espionage Act – for conspiracy to receive, obtain and disclose classified diplomatic and military documents.
Among Wikileaks’ revelations was video footage from a 2007 US Apache helicopter attack in Baghdad that killed at least nine men, including a Reuters news photographer and his driver.
The MPs’ report backs the recommendation of the UN special rapporteur on torture who called last year for the extradition to the US to be blocked.
On the claim that Ms Sacoolas “is in fact a CIA operative”, Mr Corbyn claimed: “Now we know the foreign secretary [Dominic Raab] misled the Dunn family, who are being denied justice by the US government, will the prime minister commit to his removal from office tomorrow in his reshuffle?”
Mr Johnson replied: “The Foreign Office has been told Anne Sacoolas was notified to the UK government as a spouse with no official role.
“We will continue without fear or favour to seek justice for Harry Dunn and his family and continue to seek the extradition of Anne Sacoolas from the United States.”
Mr Corbyn protested: “This lopsided treaty means the US can request extradition in circumstances that Britain cannot.”
The prime minister acknowledged: “To be frank, I think [Mr Corbyn] has a point in his characterisation of our extradition arrangements with the United States and I do think there are elements of that relationship that are imbalanced. I certainly think it is worth looking at.”
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