The Australian government has been urged to lobby Donald Trump to end the US government’s attempt to extradite Wikileaks co-founder Julian Assange from the UK.

District Judge Vanessa Baraitser said at the Old Bailey on Monday that, due to the real risk of suicide, the 49-year-old should not be extradited by “reason of mental health”.

The US has given notice it will appeal against the decision and has two weeks to lodge grounds, while Assange has been remanded in custody ahead of a bail application.

He is wanted to face an 18-count indictment, alleging a plot to hack computers and a conspiracy to obtain and disclose national defence information.

Assange was born in Queensland and is an Australian citizen, and Prime Minister Scott Morrison said he would “be able to return to Australia like any other Australian” should the appeal fail.

“It’s just a straightforward process of the legal system in the UK working its way through”, he told radio station 2GB on Tuesday.

But some of Mr Morrison’s backbenchers who have supported Assange are seeking assurances the journalist would not be extradited from Australia.

George Christensen, of the ruling Liberal National party, said Mr Trump should pardon Assange to “ensure the Deep State and a potential Biden Administration cannot pursue further action against him”.

He added: “The UK Government must release Julian Assange immediately and have him returned to Australia. He is being held without any charge, so there is no justification for him to stay in Belmarsh Prison for a moment longer.

“Furthermore the Australian Government should ensure that when he is returned to Australia, there is no avenue for an extradition from his home country to the United States.”

This is a shameful chapter of history which shows London and Canberra care more about kowtowing to Washington than they do about protecting an Australian citizen, who has never been found guilty of any offence

Andrew Wilkie, an independent MP, added: “The judgment still leaves Mr Assange desperately vulnerable to extradition to the US.

“With a US appeal looming against the decision, Australian Prime Minister Scott Morrison must pick up the phone and call US President Donald Trump and US President-Elect Joe Biden to ask them to drop the extradition bid.

“This is a shameful chapter of history which shows London and Canberra care more about kowtowing to Washington than they do about protecting an Australian citizen, who has never been found guilty of any offence.”

The case followed WikiLeaks’ publication of hundreds of thousands of leaked documents in 2010 and 2011 relating to the Afghanistan and Iraq wars, as well as diplomatic cables.

Prosecutors say Assange helped US defence analyst Chelsea Manning breach the Espionage Act in unlawfully obtaining material, was complicit in hacking by others, and published classified information that put the lives of US informants in danger.

Assange denies plotting with Manning to crack an encrypted password on US Department of Defence computers and says there is no evidence that anyone’s safety was put at risk.

His lawyers had said he faced up to 175 years in jail if convicted, although the US government said the sentence was more likely to be between four and six years.