Computer hackers are claiming victory after attacking Visa, Mastercard and PayPal for withdrawing services from WikiLeaks - and warn Twitter is their next target.
The group of web anarchists - AnonOps - have been waging a cyber war of revenge called Operation Payback.
It followed credit card companies and PayPal suspending payments to the whistleblowing website after it began releasing secret US diplomatic cables.
Their sites have been bombarded with overwhelming numbers of simultaneous, bogus visits - a tactic known as distributed denial of service (DDOS) attacks.
Activitsts urged people to "get your weapons ready" by downloading software from a link posted on Twitter. Supporters were then told to "FIRE FIRE FIRE!!!" at the agreed time to attack the websites.
We will find and will attack those who stand against WikiLeaks and we will support WikiLeaks in everything they need.
But it appears Twitter - previously a source of much WikiLeaks support - could now become a target.
The microblogging website suspended AnonOps' account last night and it has been accused of preventing the term "WikiLeaks" from appearing in its trending topics - a claim it has denied.
AnonOps has posted a statement on its website warning: "Twitter you're next for censoring WikiLeaks discussion."
A spokesman for Visa said it was "taking steps to restore the site to full operations".
The MasterCard website is now back online, although it is slow to load. The company said cardholders' payments are "secure".
In the attack on Visa, supporters were urged to 'get your weapons ready'
Other Operation Payback targets have included Swiss bank PostFinance, which froze money belonging to WikiLeaks founder Julian Assange, who is in a London prison after being arrested over sex assault claims in Sweden.
In the US Tea Party figurehead Sarah Palin said her website and credit card details had also been hacked after she criticised Mr Assange.
"This is what happens when you exercise the First Amendment and speak against his sick, un-American espionage efforts," the former governor for Alaska told ABC News.
In a statement, AnonOps - which admits DDOS attack tactics - said: "We will find and will attack those who stand against WikiLeaks and we will support WikiLeaks in everything they need."
SKY
I see the Swedish prosecutors site was attacked too.
Suppose it was inevitable leftwing brat terrorism moved into cyberspace.