Julian Assange’s European defence team have said they will try to seek asylum for him in France. Hearings over Assange’s extradition from the UK to the US on spying charges are due to start next week in London.

Éric Dupond-Moretti said the “fate and the status of all journalists” was at stake in Assange’s case. “We consider the situation is sufficiently serious,” he said, “that our duty is to talk about it” with the French president, Emmanuel Macron.

He was one of a team of lawyers lined up at a Paris news conference to explain why they view the case against Assange as unfair, citing his poor health and alleged violations of his rights while in jail in London.

French members of the team said they had been working on a “concrete demand” for Macron to grant Assange asylum in France, where he has children and where WikiLeaks had a presence at its founding.

Baltasar Garzón, the Spanish coordinator of Assange’s team, reiterated his client’s plan to claim that the Trump administration offered him a pardon in return for saying Russia was not involved in leaking Democratic National Committee emails during the 2016 US election campaign.

Garzón said Assange was “pressured by the Trump administration” but resisted, and “the order was given to demand the extradition of Julian Assange”.

The White House has firmly denied the claim. However, Garzón said that testimony and “documentary proof” of the claim would be offered to the court at the full hearing which opens on Monday.

Assange, 48, spent seven years in Ecuador’s London embassy before being evicted and arrested in April 2019. Last November, Sweden dropped a sex crimes investigation against him because so much time had elapsed.

Assange, who is Australian, has received backing from numerous quarters. The Council of Europe’s commissioner for human rights, Dunja Mijatović, added a voice of opposition on Thursday, citing concerns over Assange’s eventual treatment in a US prison and the impact on press freedoms were he to be extradited.

The shadow chancellor, John McDonnell, visited Assange in prison on Thursday and said: “I think this is one of the most important and significant political trials of this generation – in fact longer.”