Bannon gives damaging testimony against Trump's adviser

President Donald Trump's 2016 campaign CEO Steve Bannon delivered potentially damaging testimony on Friday against Roger Stone, describing communicating with Trump's longtime adviser about WikiLeaks despite Stone's denials and saying he believed Stone "had a relationship" with the website's founder.

WikiLeaks disclosed numerous stolen Democratic emails in the months before the 2016 election that was damaging to Trump's opponent Hillary Clinton. US intelligence agencies and former Special Counsel Robert Mueller determined that the emails were stolen by Russian state-backed hackers as part of Moscow's efforts to meddle in the election and boost Trump's candidacy.

"I was led to believe he had a relationship with WikiLeaks and Julian Assange," Bannon said of Stone in the third day of testimony in federal court in Stone's trial, referring to the WikiLeaks founder.

Stone - a self-described "dirty trickster" and "agent provocateur" - has pleaded not guilty to charges of obstructing justice, witness tampering and lying to the U.S. House of Representatives Intelligence Committee in its investigation into Russia interference in the 2016 election. The veteran Republican operative faces a possible decades-long sentence if convicted.

Bannon, testifying as a prosecution witness, confirmed that he and Stone had discussed WikiLeaks on several occasions before and after Bannon joined Trump's campaign in August 2016, including in an Oct. 4, 2016, exchange in which Bannon emailed Stone after an Assange news conference had failed to produce damaging information on Clinton as expected.

"He told me he had a relationship" with Assange, Bannon said, when asked by the prosecution why he chose to email Stone to ask why the news conference had been a dud. "It would be natural for me to reach out to him."

Stone, in sworn testimony to the House committee in its investigation of Russia election meddling, told lawmakers that he had never communicated with any members of Trump's campaign about WikiLeaks or Julian Assange.

Stone also is accused of denying the existence of certain emails and texts, including email exchanges with Bannon, and falsely telling the committee that a radio host and comedian named Randy Credico was his "intermediary" with Assange in July 2016.

Bannon, a prominent conservative political strategist, served as chief executive officer of the Trump campaign and later as a senior aide to Trump in the White House.

Credico, who finished his testimony earlier in the day, denied that he was an intermediary with WikiLeaks.

Prosecutors have said Stone also lied by failing to disclose he had also asked conservative author named Jerome Corsi to pass along messages and seek to gather intelligence from Assange.

The trial has been colourful at times, with Credico's courtroom impersonation of Democratic presidential candidate Bernie Sanders and testimony and evidence presented about threats by Stone to Credico's dog.

Only blocks away from the federal courthouse, the Democratic-led House is pursuing an impeachment inquiry against Trump over the Republican president's request that Ukraine investigates Democratic political rival, Joe Biden.

Credico testified on Friday he did not believe that Stone's threats to kidnap his dog were sincere, saying under cross-examination by Stone's defence attorney, Robert Buschel, that "it was hyperbole by him."

The prosecution has accused Stone of pressuring Credico to cover up lies and of seeking to prevent the radio host from cooperating with the government.

Stone sent various intimidating texts and emails, including one in which he told Credico, "You are a rat. A stoolie. ... My lawyers are dying to rip you to shreds. I am going to take that dog away from you."

Credico's statement may undercut the prosecution's claim of criminal intent to tamper with a witness, but the jury will also weigh many other comments and threats by Stone including one in which he said, "Prepare to die."