The planned extradition and prosecution of Julian Assange by the United States is a “new form of forced rendition” and a “dangerous precedent” for press freedom, according to the WikiLeaks editor-in-chief, Kristinn Hrafnsson.

Ahead of a private briefing for Australian parliamentarians on Tuesday afternoon, Harfnsson, an Icelandic-based investigative journalist, told the National Press Club in Canberra the “forced rendition” of Assange was not occurring “with a sack over the head and an orange jumpsuit but with the enabling of the UK legal system and with the apparent support of the Australian government”.

“I strongly believe that resolving this issue has important international implications,” Hrafnsson said. “Prolonging it creates an enabling environment for the deterioration of press freedom standards globally”.

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Political support for stopping the extradition of Assange has been growing in recent months and Australian MPs from across the political divide have formed the Parliamentary Friends of the Bring Julian Assange Home group. The group has membership from the LNP, National party, ALP and crossbench and is co-chaired by George Christensen and Tasmanian independent Andrew Wilkie.

Hrafnsson acknowledged the work of the friendship group during his press club address. “Thank you for getting it, Barnaby Joyce, Rebekha Sharkie, Rex Patrick, Julian Hill, Steve Georganas, Richard Di Natale, Adam Bandt, Peter Whish-Wilson and Zali Steggal.”

He also thanked a group of more than 60 doctors who have written an open letter saying they fear Assange’s health is currently so bad the WikiLeaks founder could die inside a top-security British jail.

Hrafnsson challenged Australian journalists to press the Morrison government to advocate on Assange’s behalf. “Your government did take steps to secure the freedom of James Ricketson, also of Melinda Taylor, also of Peter Greste.

“Please be direct. Please be insistent. Ask for details, not platitudes. Please be unrelenting and prepared to back each other when evasions occur,” he said. “You, above all people, are able to distinguish between publishing and espionage, a distinction the US government and its allies seem intent on erasing, and you know as well as I that if they are successful in this, then Julian Assange won’t be the last of our colleagues to have his life destroyed in this line of work.”

Assange faced allegations of sexual assault in Sweden, which he denied, when he entered the Ecuadorian embassy in London in 2012 and sought asylum because he feared being extradited to America. He spent nearly seven years in the embassy until police removed him in April after Ecuador revoked his political asylum. The Swedish investigation was dropped in November.

The British home secretary, Sajid Javid, has signed a request for Assange to be extradited to the US, where he faces charges of computer hacking. Assange faces an 18-count indictment, issued by the US Department of Justice, that includes charges under the Espionage Act. He is accused of soliciting and publishing classified information and conspiring to hack into a government computer.

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As well as pressing Assange’s case, the WikiLeaks editor-in-chief faced questions on Tuesday about the role of the organisation during the US presidential election. In November 2016, Assange issued a statement defending the role of his organisation, saying it published hacked emails from Hillary Clinton’s presidential campaign because publication was in the public interest, “not due to a personal desire to influence the outcome of the election”.

WikiLeaks did not publish any material about Donald Trump. Hrafnsson said nothing of consequence was published about Trump because WikiLeaks did not receive anything of importance that it could authenticate and publish about the candidate, who went on to win the presidential election.

Hrafnsson was asked on Tuesday whether in hindsight he felt played by the Trump campaign. The editor-in-chief was unrepentant. He said the primary judgment to be made in cases like the publication of the Clinton emails was whether the disclosure was in the public interest. He said the editorial judgment involved “evaluating the information you have in front of you”.

“If it’s authentic, you just have to decide whether it’s in the public interest or not.”