(CNN) -- Stratfor, a global intelligence company, has been hacked but it was unclear Monday whether the breach and apparent release of credit card information was the work of the activist hacking group Anonymous.
A posting on the website Pastebin said that Stratfor subscriber data, including information on 4,000 credit cards and the company's "private client" list, had been released. The posting cited AntiSec, a Web-based collaboration with the activist hacking groups Anonymous and LulzSec.
U.S.-based Stratfor, which provides independent analysis of international affairs and security threats and describes itself as a publisher of geopolitical analysis, sent an e-mail Sunday to subscribers.
"On December 24th an unauthorized party disclosed personally identifiable information and related credit card data of some of our members," it said. "We have reason to believe that your personal and credit card data could have been included in the information that was illegally obtained and disclosed."
Allen Barr of Austin, Texas, told CNN he was victimized by the misuse of his private information that was hacked from the website before it was posted on websites on the 24th.
A week ago, unauthorized charges totaling $700 were billed to his Visa debit card, he said. The total was charged in increments to a number of charities over the course of about 30 minutes, he said.
But the company quickly identified the transactions as suspicious and called Barr's house, he said. In short order, he had canceled the card, but not before his credit union checking account had been debited, he said. Rectifying that required half a day spent filing police reports and affidavits, he said.
"Two days later, they said that they would credit back my funds, pending completion of the investigation," he added.
Stratfor said the claim that the data included the firm's "private clients" was wrong.
"Contrary to this assertion the disclosure was merely a list of some of the members that have purchased our publications and does not comprise a list of individuals or entities that have a relationship with Stratfor beyond their purchase of our subscription-based publications," CEO George Friedman said in an e-mail to members.
The firm provides intelligence reports to subscribers. A recent e-mail discussed political prospects for Iraq.
The information-sharing website Pastebin posted a news release it said was from Anonymous that said the group had nothing to do with the cyberattack on Stratfor.
"Stratfor is an open-source intelligence agency, publishing daily reports on data collected from the open Internet," the posting said. "Hackers claiming to be Anonymous have distorted this truth in order to further their hidden agenda, and some Anons have taken the bait."
"The leaked client list represents subscribers to a daily publication which is the primary service of Stratfor," it continued. "Stratfor analysts are widely considered to be extremely unbiased. Anonymous does not attack media sources."
Stratfor's Friedman said the company is working closely with law enforcement.
"Stratfor's relationship with its members and, in particular, the confidentiality of their subscriber information, are very important to Stratfor and me," he wrote on the firm's Facebook page.
"We have reason to believe that the names of our corporate subscribers have been posted on other web sites," the Austin, Texas, company said. "We are diligently investigating the extent to which subscriber information may have been obtained."
Asked about the hacking, Pentagon spokesman George Little said Sunday that "Initial indications suggest that there has been no impact" to the Department of Defense grid.
Stratfor's website was not functioning Monday. A banner read, "Site is currently undergoing maintenance. Please check back soon."
Weekend online postings regarding the Stratfor situation mentioned Army Pfc. Bradley Manning, who served as an intelligence analyst in Iraq. He faces 22 charges related to the leak of nearly 750,000 U.S. military and State Department documents. Most of them ended up on the WikiLeaks website.
"While the rich and powerful are enjoying themselves with all their bourgeois gifts and lavish meals, our comrade Bradley Manning is not having that great of a time in federal custody," said a Pastebin posting. "Instead of being heralded as a fighter for free information and government transparency, he is criminalized, marginalized, and incarcerated, threatened with life imprisonment."
CNN's Barbara Starr contributed to this report.