Credit card giant MasterCard and the Swedish prosecutor's office came under cyber attack on Wednesday as WikiLeaks supporters vowed to retaliate for moves against Julian Assange after the release of U.S. diplomatic cables that angered and embarrassed Washington.

The Swedish prosecution authority, whose arrest order for Assange over accusations of sexual offenses led a British court to remand the 39-year-old WikiLeaks website founder in custody, said it had reported the online attack to police.

Of course, it's easy to think it has a connection with WikiLeaks but we can't confirm that, prosecution authority web editor Fredrik Berg told Reuters Television.

Assange supporters also went for the corporate website of credit card firm MasterCard in apparent retaliation for its blocking of donations to the WikiLeaks website.

We are glad to tell you that is down and it's confirmed! said an entry on the Twitter feed of a group calling itself AnonOps, which says it fights against censorship and copywrong.

Mark Stephens, Assange's principal lawyer in London, denied that the WikiLeaks founder had ordered the cyber strikes. Assange did not give instructions to hack the company websites, Stephens told Reuters.

MasterCard said its systems had not been compromised by what it called a concentrated effort to flood our corporate web site with traffic and slow access.

We are working to restore normal service levels, the company said in a statement. It is important to note that our systems have not been compromised and there is no impact on our cardholders' ability to use their cards for secure transactions globally.

Assange spent the night in a British jail and will appear for a hearing on December 14.

Assange, who has lived periodically in Sweden, was accused this year of sexual misconduct by two female Swedish WikiLeaks volunteers. The pair's lawyer said their claims were not a politically motivated plot against Assange.

It has nothing to do with WikiLeaks or the CIA, said lawyer Claes Borgstrom, whose website also came under cyber attack, according to officials.

Assange has angered U.S. authorities and triggered headlines worldwide by publishing the secret cables.

Australian Foreign Minister Kevin Rudd said the people who originally leaked the documents, not Assange, were legally liable and the leaks raised questions over the adequacy of U.S. security.

Mr Assange is not himself responsible for the unauthorized release of 250,000 documents from the U.S. diplomatic communications network, Rudd told Reuters in an interview.

The Americans are responsible for that, said Rudd, described in one leaked U.S. cable as a control freak.

U.S. State Department spokesman P.J. Crowley conceded that the fundamental responsibility for the leak rests inside the U.S. government where we believe a crime has been committed.

But just as clearly, what Julian Assange is doing by releasing these classified documents is putting real lives and real interests at risk, Crowley said in an e-mail message.


WikiLeaks vowed it would continue making public details of the confidential U.S. cables. Only a fraction of them have been published so far.

Assange has become the public face of WikiLeaks, hailed by supporters including campaigning Australian journalist John Pilger and British film maker Ken Loach as a defender of free speech, but he is now battling to clear his name.

Some supporters appear to want to help him. While most denial of service attacks involve botnets, programs that hijack computers and use them to target individual websites and bring them down, the current cyber attacks seem to be different.

In this case... they seem to be using their own computers, he said. Asked what that said about how many individuals might be involved: Probably hundreds at the least, could be thousands, said Mikko Hypponen, chief research officer of Finnish software security firm F-Secure.

Online payment service PayPal, which was among companies which suspended WikiLeaks' accounts used to collect donations, said it had acted at the behest of the U.S. government.

On November 27th, the State Department, the U.S. government basically, wrote a letter saying that the WikiLeaks activities were deemed illegal in the United States and as a result our policy group had to make the decision of suspending the account, Osama Bedier, PayPal's vice president of platform and emerging technology, told a conference in Paris.

Swiss PostFinance, the banking arm of state-owned Swiss Post, which also closed a WikiLeaks donation account, said it had taken countermeasures and an earlier wave of cyber attacks appeared to be waning.

The community around Julian Assange have said 'we're leaving it now, we've shown what we can do,' PostFinance spokesman Alex Josty said.


The latest cables, reported in Britain's Guardian newspaper, said Libyan leader Muammar Gaddafi made threats to cut trade with Britain and warned of enormous repercussions if the Libyan convicted of the 1988 Lockerbie airline bombing died in a Scottish jail. He was freed in August 2009.

WikiLeaks also released cables on Wednesday that showed Saudi Arabia proposed an Arab army be deployed in Lebanon, with U.S. air and naval cover, to stop Shi'ite Hezbollah militia after it seized control of parts of Beirut in 2008.

Like many of the cables, the disclosures give an insight into diplomacy which is normally screened from public view.

The original source of the leaked cables is not known, though a U.S. army private, Bradley Manning, who worked as an intelligence analyst in Iraq, has been charged by military authorities with unauthorized downloading of more than 150,000 State Department cables.

U.S. officials have declined to say whether those cables are the same ones now being released by WikiLeaks.

(Additional reporting by Michel Rose and Peter Apps in London, Emma Thomasson in Zurich, and Patrick Lannin in Stockholm; editing by Matthew Jones and Eric Beech)