Speaking from the Ecuadorean embassy in London, the whistleblower suggested the incumbent US President was trying to derail Mr Trump’s ascent to the White House by accusing Russia of interfering in the election.
The 45-year-old Australian told Fox Newsthe Obama administration was “trying to delegitimise the Trump administration as it goes into the White House".
“They are trying to say that President-elect Trump is not a legitimate President,” he added.
Trump vs Clinton Like 'Cholera vs Gonorrhoea' - Assange at Green Party Convention
Last week President Obama expelled 35 Russian diplomats in retaliation for the hacking of email accounts linked to the Democratic Party.
US security officials believe Kremlin-backed hackers accessed the servers to help Mr Trump win the presidency.
The files, taken from Hillary Clinton campaign chairman John Podesta, were then released by Wikileaks.
But Mr Trump has refused to accept the conclusion that Moscow was behind the hacking.
Incoming White House press secretary Sean Spicer said "there doesn't seem to be conclusive evidence" that the Russians were responsible.
Trump and Putin passionately kiss in street mural
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Questioned on Russia’s involvement, Mr Assange insisted Vladimir Putin’s administration was not involved.
“We can say, we have said, repeatedly that over the last two months that our source is not the Russian government and it is not a state party," he said.
“If you look at most of his [Obama’s] statements, he doesn’t say that.
“He doesn’t say that Wikileaks obtained its information from Russia, worked with Russia.”
Asked if the Podesta files changed the course of the election, Mr Assange replied: “Who knows, it’s impossible to tell. But if it did, the accusation is that the true statements of Hillary Clinton and her campaign manager, John Podesta, and the DNC [Democratic National Committee] head Debbie Wasserman Schultz, their true statements is what changed the election.”
Wikileaks’ posted a message on New Year’s Day promising the release of more documents in the coming year.
A tweet from the group’s official account read: “If you thought 2016 was a big Wikileaks year 2017 will blow you away.”
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