The Anonymous hacking collective claims it has compromised US Federal Emergency Management Agency (Fema) servers and has posted the contact information of people connected to the agency online.

Anonymous said it released the information because recent events, including the NSA surveillance revelations, have brought "oblique and cowardly implied threats against Anonymous very much back into the forefront of the hive's consciousness".

The release includes the names, mailing addresses and email addresses of contractors, subcontractors and government employees linked to Fema, including private defense contractors, federal agents and local authorities.

Much of the information was already accessible online to someone determined to find it, though Anonymous said it redacted social security numbers and login information because its "intent is not to harm, merely to issue a firm warning".

However, the mailing addresses connected to some of the people listed on the release are not publicly affiliated with their employers and Anonymous referred to them as home addresses in an email. It did respond to a question asking why this does not fall under the banner of harmful information.

Anonymous said it targeted Fema because of a training exercise the agency used in 2012 to prepare employees for a cyberattack. In the scenario, a fictional group called "The Void" launches a cyberattack on US businesses and infrastructure.

Anonymous sees The Void as a stand-in for their organization and feels that the training exercise made some unfair implications about the collective. It said actions taken by The Void "implicitly link financial gain and fraud to activist hackers". Anonymous was also upset because it believes the exercise implies the collective is anti-American.

Fema did not respond to requests for confirmation on whether its servers were compromised.

The Fema exercise occurred in 2012, but Anonymous said in a statement that it believes the exercise was used "as part of the ongoing justifications for Prism and the other NSA spy programs". With these recent developments, Anonymous said it wanted to show it "does not wave the white flag".

We are not fighting any one government or corporation, we are fighting any enemy of freedom of speech and anyone compromising the right to remain anonymous online, without fear of reprisals from governments or corporations with the legal authority or financial resources to destroy the lives of anyone who dares express opinions contrary to their own official line.

Anonymous seemed to imply a threat of its own at the end of the release and said: "Also, please return to us Barrett Brown, we are asking nicely. Pretty please, with sugar on top."

Brown has been imprisoned since September after being accused of 17 offenses springing from his affiliation with Anonymous. Brown is not a hacker but had close ties to the collective and helped publicize some of their most renowned hacks including the Stratfor hack in 2011.

The Fema exercise was co-ordinated by homeland security consulting company Obsidian Analysis, who appointed former Fema chief of staff John McNamara to be company vice-president in May. The National Level Exercise: Cybertop Capabilities Tabletop Exercise, can be downloaded from the Fema site here.