Assange, an Australian citizen, is wanted by Swedish authorities on rape charges and has been threatened with prosecution by Washington over the posting of over 250,000 US diplomatic memos on the WikiLeaks whistleblower website.
"I'm aware the US Attorney has said that US law-enforcement authorities are looking very closely at the fact that United States laws may have been breached and the Australian Federal Police are looking at whether any Australian laws have been breached," McClelland told reporters.
"We've also indicated that we'll provide every assistance to United States law-enforcement authorities," he added.
McClelland said it was possible Assange's Australian passport could be cancelled, but that this would depend on "whether it would be constructive or counter-productive to the law enforcement".
Assange, 39, is thought to be in hiding in Europe.
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