Former British ambassador Craig Murray said he has met the person who handed over the e-mails and they WERE from the Democratic National Committee (DNC).
The e-mails were released by Mr Assange’s site and caused damage to Hillary Clinton’s reputation with a number of shock revelations among tens of thousands of e-mails.
Speaking to The Guardian, Mr Murray said: “I know who leaked them.
“I’ve met the person who leaked them, and they are certainly not Russian and it’s an insider. It’s a leak, not a hack; the two are different things.
“As Julian Assange has made crystal clear, the leaks did not come from the Russians. As I have explained countless times, they are not hacks, they are insider leaks – there is a major difference between the two.”
The ex-Uzbekistan ambassador said Mrs Clinton should take account of what she did wrong – rather than making accusations about the hack.
He said: “And it should be said again and again, that if Hillary Clinton had not connived with the DNC to fix the primary schedule to disadvantage Bernie, if she had not received advance notice of live debate questions to use against Bernie, if she had not accepted massive donations to the Clinton foundation and family members in return for foreign policy influence, if she had not failed to distance herself from some very weird and troubling people, then none of this would have happened.”
Mr Assange had previously said WikiLeaks did not get e-mails related to Mrs Clinton’s campaign from a “state actor”.
Director Oliver Stone, a vocal supporter of the WikiLeaks founder, also made the shock claims about the release of the e-mails three months ago.
Mr Stone, who has recently produced a biopic of Edward Snowden, said he believed the hack was perpetrated by Democrats within the committee.
Reports following the release of the e-mails suggested Russian hackers got into the DNC e-mail server and fed information to WikiLeaks in an attempt to influence the US presidential election.
During an interview with CNN’s Christiane Amanpour, Mr Stone called the accusations a “great fiction” and suggested foul play by the DNC.
The director revealed intelligence experts he spoke to indicated the DNC hack was “probably an inside job.”
The revelations from the hack led directly to the resignation of DNC chair Debbie Wasserman Schultz and other high-level officials.