Assange's remark came at the end of a contentious interview Friday with "Real Time" host Bill Maher, during which the two discussed WikiLeaks' recent disclosure of Democratic National Committee emails and voicemails. Assange, who has vowed to release more information
to damage Hillary Clinton's campaign, was asked by Maher, a Clinton supporter, whether he plans to similarly disrupt Trump's presidential prospects.
"Why don't you hack into Donald Trump's tax return?" Maher asked.
"Well, we're working on it," responded Assange, who did not provide further information.
But a message from WikiLeaks' official Twitter account Saturday morning dismissed Assange's statement, claiming it was meant in jest.
"WikiLeaks isn't 'working on' hacking Trump's tax-returns. Claim is a joke from a comedy show. We are 'working on' encouraging whistleblowers."
Trump has repeatedly refused to release his tax returns
to the public, a common practice for modern presidential candidates, saying he's under audit.
The bucking of the decades-long tradition has fueled considerable criticism and speculation over what the documents might contain, including whether Trump has any business dealings with Russia
The US rival has been accused of being behind the hacked DNC emails, and the resulting controversy led to the resignation
of DNC Chairwoman Debbie Wasserman Schultz and the ouster of several other top DNC officials
. Assange told CNN last week
his organization has "more material related to the Hillary Clinton campaign."
"Why haven't we seen anything hacked from the Trump campaign?" Maher asked Assange, who was speaking via satellite from the Ecuadorian embassy in London, where he faces extradition over sexual assault allegations. "I mean, obviously we know these (files) came from Russia. It looks like you are working with a bad actor, Russia, to put your thumb on the scale, and basically, f--- with the one person who stands in the way of us being ruled by Donald Trump."
Assange pushed back, saying, "Everyone knows the source of what we published. The source is the Democratic Party."
Assange also swiped at National Security Agency whistleblower Edward Snowden, who recently criticized
WikiLeaks for its "hostility to even modest curation" of its document dumps. The WikiLeaks founder said he "saved (Snowden's) ass," and implied Snowden's recent criticism of WikiLeaks' tactics was in pursuit of a pardon from President Barack Obama.