WikiLeaks Supporters Target Visa, MasterCard

Story updated to include new MasterCard and Visa statement

SAN FRANCISCO (TheStreet) -- Visa (V) shares were slipping in after-market trading after a report came out noting that the payment network's website was down this afternoon.

Earlier Wednesday, payment network rival, MasterCard's (MA) website was also down, one day after the payments firm said it was disassociating its network from the controversial WikiLeaks website.

Visa said in a statement that its corporate website was "currently experiencing heavier than normal traffic." The company is "taking steps to restore the site to full operations within the next few hours."

However its processing network, which handles cardholder transactions, is functioning normally and "cardholders can continue to use their cards as they routinely would" since account data is not at risk, it said.

MasterCard issued a statement Wednesday saying that it had made "significant progress in restoring full-service to its corporate website."

The card network's "core processing capabilities have not been compromised and cardholder account data has not been placed at risk," the statement said. "While we have seen limited interruption in some web-based services, cardholders can continue to use their cards for secure transactions globally."

At last check, it seemed that some functionality to MasterCard's website had been restored but not all. Visa's website was still down.

According to several published reports, internet hackers, supposedly supporters of WikiLeaks, have bombarded both companies websites in order to overwhelm the systems.

The Financial Times said that an anonymous campaign group, supporters of what it calls "Operation Payback," is claiming on Twitter that it was responsible for the disruption on MasterCard's website.

A report by Silicon Valley Insider during the afternoon was first to attribute the same group to causing Visa's website outage as well.

A Visa spokeswoman said the company could not comment on who caused the outage, only saying the matter was "still being investigated."

MasterCard issued a statement earlier Wednesday saying that it was experiencing "heavy traffic on its external corporate website." The company is working to restore normal speed of service.

"There is no impact whatsoever on our cardholders ability to use their cards for secure transactions," MasterCard said.

The firm said Tuesday that it was "taking action to ensure that WikiLeaks can no longer accept MasterCard-branded products" and accused the site of engaging in illegal activity. PayPal, a subsidiary of eBay (EBAY) is also blocking the website.

PayPal also had issues with its website this week.

WikiLeaks told the FT that following founder Julian Assange's arrest on Tuesday, it "will not be gagged, either by judicial actions or corporate censorship."

WikiLeaks named Visa, MasterCard, PayPal, Amazon (AMZN) and EveryDNS, a domain name service provider, as examples of companies that had cut links.

The FT quoted sources as saying more attacks are likely.

PayPal's website was working at last check, as was Amazon's and EveryDNS.

Visa shares rose 1.4% to $77.94, but slipped after the market closed. MasterCard shares also closed up 1.6% to $250.64, but more recently were falling.

-- Written by Laurie Kulikowski in New York.

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