A member of Anonymous, the group that launched a cyber-attack on some of America's biggest corporations, has defended the action saying: "I don't regret anything that I've done. I would do it all again."

Called Operation Payback, the cyber-assault was a denial of service attack intended to avenge the campaign against the WikiLeaks website and the pursuit of its founder Julian Assange.

An interview with one of the men who is alleged to have organised Operation Payback is being aired on the ABC's Four Corners program tonight.

Four Corners interviewed the man in Washington early last year as it pieced together the story of Private Bradley Manning and his alleged theft of US state secrets.

At that stage the man was concerned the interview, if it was shown, could allow US authorities to track him and charge him.

In July last year, the man was arrested and subsequently charged, together with other hacktivists in the United States and Europe. Now the interview is being shown tonight for the first time.

The man admitted to Four Corners that he had mixed thoughts about giving an interview, saying he was "actually kind of terrified" to be filmed in Washington, but he added, "If we have been identified and they decide to take action against us, they're going to attempt to silence us and the story might not even get out."

The story tells how in December 2010, nearly 8,000 hackers launched a denial of service attack on some of America's biggest corporations including Visa, Mastercard and Paypal, which were refusing to process donations to WikiLeaks.

The operation was organised on AnonOps, a focal meeting point for the worldwide group Anonymous. The AnonOps member interviewed for tonight's program says that Operation Payback was carried out in support of WikiLeaks: "They were discussing various options and the suggestion came up that since they cut off the funding, why don't we cut off theirs and it was born out of that."

The charges against those alleged to have organised Operation Payback carry possible fines of $US1 million, and 15-year jail terms.

WikiLeaks saga

Bradley Manning is to face a court martial later this year. ( Twitter )

US soldier Bradley Manning is alleged to have leaked more than 250,000 US State Department diplomatic cables and more than 500,000 US Army logs to WikiLeaks. Private Manning faces a court martial later this year on 22 charges, one of which - "aiding the enemy" - is a capital offence. However, military prosecutors have indicated that they will not be seeking the death penalty if Private Manning is convicted.

As Julian Assange fights to prevent his own extradition to Sweden to face questioning on allegations of sexual assault, speculation is mounting that a Grand Jury sitting in secret in Washington has already prepared a sealed indictment, which would allow American officials to seek his onward extradition to the United States.

Australia's Federal Government has refused to confirm this. In Question Time on May 31, Prime Minister Julia Gillard said: "At this stage we do not have any advice from the United States that there is an indictment against Mr Assange or that the United States has decided to seek his extradition."

But evidence that an indictment may have been issued comes from confidential emails hacked into last December, allegedly by members of Anonymous, and published by WikiLeaks. The emails were written by staff at the Texas-based private intelligence firm Stratfor, who have close ties with the US administration.

One internal email, written by Stratfor's vice president of intelligence, Fred Burton, says: "Not for pub – We have a sealed indictment on Assange. Pls protect."

Until now the company has refused to say whether this email is genuine. Stratfor chief executive George Friedman says on the company website: "Some of the emails may be forged or altered to include inaccuracies. Some may be authentic. We will not validate either, nor will we explain the thinking that went into them. Having had our property stolen, we will not be victimised twice by submitting to questions about them."

But following an approach from Four Corners, Stratfor has told the ABC: "We have made the practice not to comment on stolen emails. However, given the extensive coverage of this email, we will make an exception here. The email is authentic. It represented information from a source who asked that it not be published.

"However, in our further investigation we determined the source to be unreliable and could get no further information on the subject. At this time, there are many unsubstantiated claims floating around on this subject. We therefore never published anything on it. We have no special insight on an indictment nor ever claimed to have. This email represents one of many passed around internally each day on many subjects. It was dismissed by us as unreliable information."

Watch Quentin McDermott's full story - WikiLeaks, The Forgotten Man - on the Four Corners website.