LONDON - Hackers rushed to the defense of WikiLeaks yesterday, launching attacks on MasterCard, Visa, Swedish prosecutors, a Swiss bank and others who have acted against the site and its jailed founder, Julian Assange.
Internet "hacktivists" operating under the label Operation Payback claimed responsibility in a Twitter message for causing severe technological problems at the website for MasterCard, which pulled the plug on its relationship with WikiLeaks a day earlier.
MasterCard acknowledged "a service disruption" involving its Secure Code system for verifying online payments, but spokesman James Issokson said consumers could still use their credit cards for secure transactions. Later in the day, Visa's website was inaccessible.
The online attacks are part of a wave of support for WikiLeaks that is sweeping the Internet. Twitter was choked with messages of solidarity for the group, while the site's Facebook page hit 1 million fans.
Late yesterday, Operation Payback itself appeared to run into problems, as many of its sites went down. It was unclear who was behind the counterattack.
MasterCard is the latest in a string of U.S.-based Internet companies, including Visa, Amazon.com, PayPal Inc. and EveryDNS, to cut ties to WikiLeaks in recent days amid intense U.S. government pressure. PayPal was not having problems yesterday, but the company said it faced "a dedicated denial-of-service attack" on Monday.
WikiLeaks' extensive releases of secret U.S. diplomatic cables have embarrassed U.S. allies, angered rivals, and reopened old wounds across the world. U.S. officials say other countries have curtailed their dealings with the U.S. government because of WikiLeaks' actions.
Assange is in a British prison fighting extradition to Sweden over a sex crimes case. Recent moves by Swiss Postfinance, MasterCard, PayPal and others that cut the flow of donations to the group have impaired its ability to raise money.
Undeterred, WikiLeaks released more confidential U.S. cables yesterday. The latest batch showed the British government feared a furious Libyan reaction if the convicted Lockerbie bomber wasn't set free and expressed relief when they learned he would be released in 2009 on compassionate grounds.