Wikileaks has offered to help US President Barack Obama authenticate spy agencies' assessment that Russia was behind the leak of hacked Democratic emails during the presidential election.

Wikileaks published the leaked emails over the summer, the messages having been hacked from the Democratic National Convention and the account of Hillary Clinton campaign chairman John Podesta.

The group tweeted on Friday: "Obama should submit any Putin documents to WikiLeaks to be authenticated to our standards if he wants them to be seen as credible."

On Saturday it was revealed that the FBI and James Clapper, the US director of national intelligence, had come to agree with the CIA's assessment that Russia interfered in the election, in part to help Donald Trump win the White House.

Mr Assange had previously claimed in an interview on the Russian state-funded RT channel that Moscow was not the source of the emails. RT says on its website that it seeks to acquaint international audiences "with a Russian viewpoint on major global events".

Mr Assange has been living in the Ecuadorian embassy in London since he was granted political asylum in 2012. His self-imposed exile began to avoid extradition to Sweden, where he is wanted for questioning over allegations of sexual assault.