The judge, Vanessa Baraitser, briefly adjourned proceedings at the Old Bailey after the 49-year-old Australian interrupted the evidence of US human rights lawyer Clive Stafford Smith on Tuesday morning.

The outburst could not be heard by journalists, who are following proceedings on a videolink from another court.

"The witness must be allowed to give their evidence free from interruption," the judge told Assange after he was allowed to speak with his lawyers.

"You will hear things, no doubt many things, you disagree with during these proceedings."

She added: "If you interrupt proceedings it is open to me to proceed in your absence. This is obviously something I would not wish to do.

"You must allow the witness to speak without interruption so they can give their evidence."

The defence witness described how WikiLeaks helped expose alleged US war crimes in Afghanistan and shone a light on Guantanamo Bay.

Mr Stafford Smith, who founded the Reprieve organisation, said: "I say this more in sadness than anger. I would never have believed that my government would do what it did.

"We are talking about criminal offences of torture, kidnapping, rendition, holding people without trial."

He said leaks had revealed the US allegations against clients held in Guantanamo, which he was then able to prove as "nonsense".

But cross-examining, James Lewis QC, for the US, suggested that Assange was not being prosecuted in the US for publishing cables, which had previously been reported in the New York Times and Washington Post, or hundreds of thousands of others.

He said: "Mr Assange is not being prosecuted for publishing those cables or anything other than the documents which contain the names of informants which put their lives at risk."

Assange has been held on remand in Belmarsh prison since last September after serving a 50-week jail sentence for breaching his bail conditions while he was in the Ecuadorian embassy in London for almost seven years.

On Monday, he was arrested in the cells at the Old Bailey over a new US indictment lodged in June, including 18 charges of plotting to hack computers and conspiring to obtain and disclose national defence information.

If convicted, he faces a maximum possible penalty of 175 years in jail.

The hearing, which is expected to last for around four weeks, continues.

Australian Associated Press