WikiLeaks has released the first 200 of a cache of 5m emails obtained from the servers of Stratfor, a US-based intelligence firm.

The emails originated not from a whistleblower, but instead from a series of hacking attacks against Stratfor in December 2011, carried out by the online activist collective Anonymous.

Anonymous apparently passed the emails to WikiLeaks in the weeks following the attack. The whistleblowing website then recruited, according to its statement, 25 media partners to work on the document cache.

Stratfor describes itself as a provider of "strategic intelligence on global business, economic, security and geopolitical affairs", with a claimed 300,000 subscribers.

WikiLeaks said the documents contained details of the inner workings of the private intelligence agency, links between government and private intelligence, and commentary on WikiLeaks itself.

"The material contains privileged information about the US government's attacks against Julian Assange and WikiLeaks and Stratfor's own attempts to subvert WikiLeaks," the whistleblower website said.

"There are more than 4,000 emails mentioning WikiLeaks or Julian Assange. The emails also expose the revolving door that operates in private intelligence companies in the United States."