Anonymous says its next target is Iran.

The hacker group Anonymous has its next denial-of-service (DoS) target in sight: Iran, CNET has learned.

Members of the loosely organized group are planning "Operation Iran," an attack designed to shut down Iranian Web sites beginning Sunday, according to their latest online proclamation. May 1 is International Worker's Day.

"The people of Iran have the admiration of Anonymous, and the entire world," the statement says. "We can see that Iran still suffers at the hands of those in power. Your former government has seized control, and tries to silence you. People of Iran--your rights belong to you."

The operation seemed to already have begun late today with Web page defacements ostensibly targeted at Iranian hackers. Anonymous left messages on several Web sites that had allegedly been previously attacked by the Iranian Cyber Army, including the site of a Canadian information systems firm and the site of a Ukrainian dancing group, according to an observer on an Anonymous Internet Relay Chat channel that members use to coordinate their operations.

Anonymous is known for its renegade cyberattacks in defense of perceived underdogs or to support freedom of expression or other anti-establishment causes. In defense of whistle-blowing site WikiLeaks, the group targeted PayPal, Visa, MasterCard, and other companies late last year that had stopped enabling WikiLeaks to receive contributions.

Earlier this month, Anonymous targeted Sony in protest of the company's treatment of Sony PlayStation hacker George Hotz. Hotz and Sony have since settled the lawsuit Sony filed, and Anonymous has denied any involvement in a recent serious breach that exposed information of millions of Sony PlayStation Network customers.

Other Anonymous targets have been: Broadcast Music Inc., the Church of Scientology' the governments of Egypt, Iran, and Sweden' the Westboro Baptist Church' conservative activist billionaires Charles and David Koch and their companies' as well as security firm HBGary Federal, which had reportedly been working with the FBI to identify the leaders of Anonymous.