Messages from U.S. government agencies and Fortune 500 companies are among 5 million e-mails WikiLeaks said it has from the global intelligence firm Stratfor.
The whistle-blowing Web site said from London the e-mails, which it began releasing Monday, "expose the revolving door that operates in private intelligence companies in the United States."
Stratfor said in December its data servers were hacked by the group Anonymous, which has aligned itself with WikiLeaks.
WikiLeaks didn't confirmed the e-mails were turned over to it by Anonymous but the hacker group's Twitter page had a post that spoke of "the amazing partnership between #Anonymous and #WikiLeaks to make all 5 MILLION [e-mails] public," Time magazine reported.
Stratfor called the release "a deplorable, unfortunate -- and illegal -- breach of privacy," and said it questioned the veracity of the e-mails, writing that some may be authentic but others "may be forged or altered to include inaccuracies."
Stratfor said it would not "explain the thinking that went into" the e-mails and that its data servers were "secure and protected."
WikiLeaks said the e-mails "show Stratfor's web of informers, payoff structure, payment laundering techniques and psychological methods."