A group of shadowy hackers responsible for a string of recent high-profile cyberattacks has claimed to have stolen email addresses and passwords from associates of an FBI-affiliated security program.

The hackers who call themselves "Lulz Security," or LulzSec, said they had attacked the website of the Atlanta chapter of InfraGard in retaliation for US efforts to classify hacking as an act of war.

Lulz Security published a list online of around 180 email addresses and passwords which the group said were obtained from the InfraGard website.

"We also took complete control over the site and defaced it," Lulz Security said in a statement at their website, Lulzsecurity.com.

The InfraGard Atlanta website was "under construction" on Monday.

On its website, InfraGard describes itself as a partnership between the FBI and the private sector "dedicated to sharing information and intelligence to prevent hostile acts against the United States."

Its members include businesses, academic institutions, state and local law enforcement agencies, and others.

"InfraGard and the FBI have developed a relationship of trust and credibility in the exchange of information concerning various terrorism, intelligence, criminal, and security matters," the website says.

"InfraGard members gain access to information that enables them to protect their assets and in turn give information to government that facilitates its responsibilities to prevent and address terrorism and other crimes," it says.

There was no immediate reply from InfraGard to an AFP inquiry about the hacking claim.

Lulz Security last week claimed to have compromised more than one million passwords, email addresses and other data from SonyPictures.com, a site which features movie trailers and email updates on upcoming releases.

The group posted thousands of stolen Gmail, Hotmail, AOL, Yahoo and other email addresses and passwords on Pastebin where they were publicly accessible.

Sony Pictures Entertainment apologized over the weekend for the data breach.

In late May, Lulz Security targeted the website of the US non-profit Public Broadcasting Service in retaliation for a film it made about WikiLeaks called "Frontline: Wiki Secrets."

The hackers marred PBS Web pages with graffiti, exposed account information of member stations, and posted a fake story about the late rap musician Tupac Shakur being alive in New Zealand.