US security think tank Strategic Forecasting Inc (Stratfor) said its website had been hacked and that some of the names of corporate subscribers had been made public.
Stratfor said the breach came from an unauthorized party, while activist hacker group Anonymous claimed responsibility.
"As a result of this incident the operation of Stratfor's servers and email have been suspended," the Austin-based company said in an email on Sunday.
Hackers claiming to be the group Anonymous said they had obtained around 4,000 credit card details, passwords and home addresses on Stratfor's private client list, which was posted on information-sharing website Pastebin.
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