Mr Dunn's family is calling on Foreign Secretary Dominic Raab to halt the extradition process for Assange, ahead of the beginning of the first full court hearing on Monday.

The Mail on Sunday quoted Radd Seiger, the Dunn family spokesman, as saying: "Despite its disgraceful refusal to extradite Anne Sacoolas, the US continues to seek the extradition of people in the UK such as Julian Assange. In doing so, they are demonstrating an extraordinary amount of hypocrisy.

"As Dominic Raab told us when we met with him on January 27, 'we are reviewing all options'. We want him now to exercise the option of not extraditing Julian Assange to the US."

Assange, 48, is being held in Belmarsh Prison in south-east London and is wanted in the US to face 18 charges over the publication of US cables a decade ago. If found guilty he could face a 175-year prison sentence.

Mr Dunn's family has previously called for the Duke of York to co-operate with law enforcement in the US amid allegations around the royal's friendship with billionaire paedophile Jeffrey Epstein.

At a press conference earlier this month, Mr Seiger joined a lawyer for alleged victims of Epstein to call for both Mrs Sacoolas to return to the UK and Andrew to face questioning from the FBI in the US.

Allegations about Andrew have surfaced from Virginia Giuffre, who claims she was trafficked by Epstein and alleges the duke slept with her on three separate occasions, including when she was 17 - still a minor under US law.

Andrew strenuously denies the allegations.