Role of Australian diplomacy in Julian Assange's release

Australia's prime minister said Wednesday a string of recent non-disclosed missions to the United States helped forge the plea deal that freed Julian Assange.

The 52-year-old WikiLeaks founder landed in Canberra hours earlier, after earning his liberty by pleading guilty to a single count of conspiracy to obtain and disseminate US national defence information.

He was sentenced by a court in the US Pacific territory of Northern Mariana Islands to time already served in London's high-security Belmarsh prison -- five years and two months -- and allowed to walk free.

The US Department of Justice had to make a "range of decisions" for the plea deal to proceed, Anthony Albanese told a news conference in Canberra, stressing that the US department was independent and "not subject to political influence".

A "whole range of people" had visited the United States as the deal was worked out, the Australian leader told reporters.

"I am surprised that some of it was missed by the people in this room -- some of the visits -- but it's not up to me to indicate that," Albanese said.

He advised journalists to "go back and look at some diaries and who has travelled to the United States in recent months".

Albanese said he had exchanged "directly" with Assange's lawyers during the negotiations.

Australia's high commissioner to the United Kingdom, Stephen Smith, also acted as a conduit for communication, visiting Assange in Belmarsh, the prime minister said.

"The details of the plea deal were worked through over a period of time," he said.

"This was the only way that I could see a resolution being achieved -- and the objective here was to conclude these matters."

Albanese said he had never met with Assange but spoke with him the moment his jet touched down in Canberra as part of a mutually agreed plan.

"I had a very warm discussion with him this evening. He was very generous in his praise of the Australian government's efforts," he added.

"The Australian government stands up for Australian citizens. That's what we do."

Also watch: Julian Assange pleads guilty in US court, secures freedom