The 50-year-old Australian was dragged from London's Ecuador Embassy on April 11 in 2019 to face extradition to the United States on espionage charges over WikiLeaks' release of confidential US military records and diplomatic cables.

He has since been held at a high-security prison in Belmarsh, southeast of London, and last month married attorney and long-term partner Stella Moris from within the walls.

Three years on, Australia's Media, Entertainment and Arts Alliance has called on the federal government - now in caretaker mode ahead of the May 21 poll - to use its close ties with the US and UK to end the extradition push and drop all 18 charges against him.

The union, of which Mr Assange has been a member since 2009, argues the scope of the US charges could imperil any journalist around the world who writes about its government.

"Julian Assange's work with WikiLeaks was important and in the public interest: exposing evidence of war crimes and other shameful actions by US soldiers in Iraq and Afghanistan," MEAA Media Federal President Karen Percy said on Monday.

"The stories published by WikiLeaks and its mainstream media partners more than a decade ago were picked up by news outlets around the world. The charges against Assange are an affront to journalists everywhere and a threat to press freedom.

"The US government must see reason and drop these charges, and the Australian government should be doing all it can to represent the interests of an Australian citizen."

In December, the UK's High Court overturned a ruling the publisher should not be extradited to the US as his mental health problems meant he would be a suicide risk.

He was then denied permission to launch an appeal but could still challenge the decision by judicial review once the UK government ratifies his extradition.

WikiLeaks was awarded the Walkley Award for Most Outstanding Contribution to Journalism in 2011, one of Australia's most prestigious media prizes.

Australian Associated Press