Moneybookers terminated its relationship with WikiLeaks in August, claiming that the clandestine organisation had been placed on a US watchlist in the wake of damaging leaks about US activities in Afghanistan.

The attack on Moneybookers took the site offline briefly this morning after a group of several hundred attackers fixed it in their targets.

MasterCard, whose corporate Website was removed from the Internet for the best part of the day by a concerted attack earlier in the week, has also come under fire again, with reports that the site was knocked out briefly on Friday afternoon.

The latest action follows the arrest of a teen hacker in Holland in connection with the assaults on Mastercard, Visa and PayPal. Within hours of the arrest going public, the Web sites of police and prosecutors in the Netherlands also began to crumble.

Others to feel the force of Internet dissenters include outspoken US republican Sarah Palin, whose credit card accounts were reputedly hacked after she publicly said WikiLeaks founder Julian Assange had "blood on his hands."

Anonymous has won much publicity for WikiLeaks, but the lack of a command and control structure within the group is beginning to lessen its effectiveness, as hackers take a scattergun approach to potential targets. An attempt at bringing some structure to the collective appeared on the Web Friday morning, with the release of a press statement elucidating the aims and objectives of the movement.

"Anonymous is not a group of hackers. We are average Interent Citizens ourselves and our motivation is a collective sense of being fed up with all the minor and major injustices we witness every day," the statement read. "We do not want to steal your personal information or credit card numbers. We also do not seek to attack critical infrastructure of companies such as Mastercard, Visa, PayPal or Amazon. Our current goal is to raise awareness about WikiLeaks and the underhanded methods employed by the above companies to impair WikiLeaks' ability to function."

The statement went on to say that an attempt to take on Amazon was aborted in fear of a consumer backlash in the run up to Christmas.

"The continuing attacks on PayPal are already tested and preferable," the statment continues. "While not damaging their ability to process payments, they are successful in slowing their network down just enough for people to notice and thus, we achieve our goal of raising awareness."

PayPal issued an update on site status on the company's corporate blog late Thursday: "We can confirm that there have been multiple attempted distributed denial of service (DDoS) attacks on www.paypal.com this week. In addition, our API site api.paypal.com was targeted today. The attacks were not successful. Our customers may see slightly slower load times this week, but the attacks have not significantly impacted payments."