"If you interrupt proceedings and disrupt a witness who is properly giving their evidence, it is open to me to continue without you in your absence," Baraitser said.

Assange and WikiLeaks enraged the US government a decade ago by publishing thousands of secret American documents. Assange's supporters see him as a champion of free speech exposing abuses of power and hypocrisy by Washington.

"This is obviously not something I wish to do. I am, therefore, giving you a clear warning."

The US authorities accuse Australian-born Assange, 49, of conspiring to hack government computers and of violating an espionage law in connection with the release of confidential cables by WikiLeaks in 2010-2011.

Assange's outburst occurred as the court heard on Tuesday from Clive Stafford Smith, founder of the London-based charity Reprieve, who argues that the Wikileaks disclosures had been instrumental in challenging the US on illegal drone strikes and the secret detention of suspects.

Stafford Smith, a dual US-UK national, said the leaked information had contributed to court findings that criminal proceedings should be taken against senior US officials.

"I say this more in sadness than anger. I would never have believed that my government would do what it did," he said. "We are talking about criminal offences of torture, kidnapping, rendition, holding people without trial."

Assange and WikiLeaks enraged the US government a decade ago by publishing thousands of secret American documents. Assange's supporters see him as a champion of free speech exposing abuses of power and hypocrisy by Washington.