Trump conditionally ‘offered pardon’ to Assange: report

US President Donald Trump promised to pardon WikiLeaks founder Julian Assange if he denied Russia leaked emails of his 2016 election rival's campaign, a London court was told on Wednesday.

Assange's lawyer Jennifer Robinson said in a document that Trump relayed the offer through former US Congressman Dana Rohrabacher, the UK's domestic Press Association news agency reported.

The White House quickly issued a denial that Trump had dangled a pardon in exchange for help in the Russia controversy, which has cast a shadow over his first term in office.

"The president barely knows Dana Rohrabacher other than he's an ex-congressman. He's never spoken to him on this subject or almost any subject. It is a complete fabrication and a total lie," Trump press secretary Stephanie Grisham said in a statement.

The revelation came at a case management hearing at Westminster Magistrates' Court before Monday's formal start of Washington's extradition request for him to face espionage charges. If found guilty in the United States, he could be jailed for 175 years.

Assange's defence cited a statement from Robinson in which she said that Rohrabacher had been to see Assange and said "on instructions from the president, he was offering a pardon or some other way out, if Mr Assange... said Russia had nothing to do with the DNC leaks".

District Judge Vanessa Baraitser said the evidence was admissable.

Rohrabacher on Tuesday evening denied the allegations that he had offered Assange a deal.

US intelligence agencies have concluded Russia hacked into the computer servers of the Democratic National Committee (DNC) during Trump's campaign against Democratic rival Hillary Clinton. WikiLeaks later published the emails, which proved politically damaging to Clinton, before the November 2016 vote.

Australian national Assange, 48, is facing 18 counts in the US -- 17 of them under the Espionage Act.