"There is more the Australian government can do, and I think when we hear some of the stuff that's going to come to light next week, there's more that will be done," Mr Christensen said.
"I think that now is a time that the government that I'm part of needs to be standing up and saying to both the UK and the US: 'enough is enough, leave our bloke alone and let him come home'."
The politicians were also briefed by Mr Assange's legal team during the trip, which Mr Wilkie previously said he took at his own expense.
They both described Mr Assange as "a man under serious pressure" given his confinement and his upcoming extradition trial, which is scheduled to begin next week.
"What I have seen today probably proves there has been ongoing issues, isolation being one of them, that has taken place in this prison behind us, that probably led to a depleted, or less than normal state of mind he is in now," Mr Christensen said.
Australian MPs call for government to support WikiLeaks founder Julian Assange
Late last year, a coalition of doctors urged the Australian government to lobby for Mr Assange to be released due to concerns for his health.
The United Nations' Special Rapporteur on Torture, Nils Melzer, has also previously found that Mr Assange, who is an Australian citizen, has been psychologically tortured.
Last week, Mr Wilkie said the purpose of the trip was to "check on Julian's health and welfare" and "see firsthand the circumstances of his incarceration".
"Although he doesn't have the support of the Australian government, he does have the support of a great many people right around the world, especially in Australia," he said.
"The fact is, he [Mr Assange] has not been convicted of any crime ... he reported on and published information in the public interest, and in particular, evidence of US war crimes."
WikiLeak's editor Kristinn Hrafnsson has said Mr Assange's publishing activities were in the public interest and, despite US claims, have not resulted in any persons coming to harm.
He believes the case is purely political and gave the example of then CIA Director Mike Pompeo describing WikiLeaks as a "hostile non-state intelligence organisation" in 2016.
"This is a very political case," he said. "Therefore, of course, we need to rely on politicians to turn this around."