Julian Assange has insisted that hacked emails from a top aide to US presidential candidate Hillary Clinton are not from "state parties".
Whistleblowing organisation WikiLeaks has been releasing a series of emails from Ms Clinton's campaign chairman John Podesta which have featured in the bitterly fought election campaign against Donald Trump.
The Democrats have questioned the authenticity of the WikiLeaks releases and said the emails were hacked as part of an effort by the Russian government to influence the election.
Mr Assange, who has been living inside the Ecuadorian Embassy in London for over four years, said in a statement: "WikiLeaks' sources for the Podesta emails currently being published are not state parties.
"We have independently authenticated the emails. WikiLeaks has a decade-long, perfect record in the accurate authentication of leaked documents.
"The original sources of the Podesta emails are Hillary Clinton campaign chairman John Podesta and his correspondents."
Mr Assange said WikiLeaks has two substantive mandates - to protect the identity of its sources and to maximise the uptake of its publications.
He added: "We do not reveal details as to our sources.
"Occasionally these two mandates are in conflict when the subject of our publications has substantial media connections. This is the case for the Podesta emails.
"In such a case, saying nothing leads to a vacuum into which false claims about our sources can be projected. We tolerate such claims until they are used to distract from the publication.
"After careful consideration of the source protection requirements involved, we are confident that eliminating state parties does not appreciably increase the risks to our sources for this publication."
Mr Assange is wanted for questioning in Sweden over a sex allegation which he denies. He believes he will be extradited to the US if he leaves the embassy building.