During a visit to Australia as part of high level talks, US Secretary of State Antony Blinken said Mr Assange was accused of "very serious criminal conduct" .
Asked how he was continuing to press Australia's position to the US as ambassador, Mr Rudd said his responsibility to engage on behalf of all Australians included Mr Assange.
"As for Secretary Blinken's statements recently, that's to be anticipated from the administration, reflecting their concerns about the history of the case," he told reporters in Canberra on Wednesday.
"We in Australia have our own concerns that we continue to reflect and my job as Australia's leading diplomat in the US is to engage effectively, which usually means silently with the US administration, in order to maximise our prospects.
"The prime minister has already made clear that this has gone on for too long. I agree with him."
Since winning office in 2022, the Albanese government has been advocating for the US pursuit of Assange to end.
Mr Assange, an Australian citizen, published a trove of classified documents more than a decade ago.
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