Officials say Russian hackers used third party

President Donald Trump. Photo / Supplied

United States intelligence agencies obtained what they considered to be conclusive evidence after the November election that Russia provided hacked material from the Democratic National Committee to WikiLeaks through a third party, three US officials said yesterday.

Meanwhile, President-elect Donald Trump voiced new doubts that Russian hackers attempted to influence the country's presidential election on his behalf, while WikiLeaks founder Julian Assange said "a 14-year-old kid could have hacked" the computer of Hillary Clinton campaign chairman John Podesta.

Assange, who was being interviewed in the Ecuadorian embassy in London, has repeatedly insisted that WikiLeaks' source for the emails from Podesta and the Democratic National Committee was not the Russian Government or any "state party". He did not comment on a third party.

In an interview with PBS, outgoing CIA Director John Brennan said anyone who doubted the connection between Russia and the hacking should take a look at an intelligence report to be handed to Obama today and Trump tomorrow. Of Assange, Brennan said: "Well, he's not exactly a bastion of truth and integrity."

Trump, who is to meet intelligence chiefs over the hacking, appeared more inclined to trust Assange.

"Julian Assange said 'a 14 year old could have hacked Podesta' - why was DNC so careless? Also said the Russians did not give him the info!" Trump said on Twitter.

That prompted White House spokesman Josh Earnest to ask, "Who are you going to believe?"

Hillary Clinton. Photo / Supplied

The three US officials, meanwhile, said US officials had concluded months earlier that Russian intelligence agencies had directed the hacking, but had been less certain that they could prove Russia also had controlled the release of information damaging to Clinton, the Democratic presidential candidate.

They said the post-election intelligence gave the Obama Administration greater certainty about the full role of the Russian Government in the hacking and leaks of documents than it had on October 7, when the US intelligence agencies had said they were "confident" Russia orchestrated the hacking.

The additional intelligence also informed President Barack Obama's decision to retaliate on last week by expelling 35 suspected Russian spies and sanctioning two Russian spy agencies, four intelligence officers and three companies, a decision that capped four months of debate at the White House about how to respond, the officials said.

The officials declined to describe the intelligence obtained about the involvement of a third party in passing on leaked material to WikiLeaks, saying they did not want to reveal how the US Government had obtained the information.