NEW YORK - US authorities said on Tuesday top members of the LulzSec computer hacking group were arrested and its leader had previously pleaded guilty to carrying out over a dozen cyber attacks on major companies. Hector Xavier Monsegur, known as “Sabu,” was charged with 12 criminal counts of conspiracy to engage in computer hacking and other crimes in court documents made public on Tuesday. He admitted to hacks on the websites of eBay’s PayPal, MasterCard Inc and Visa Inc, according to court papers. The charges against him, in a case that was opened last summer, were filed in federal court in New York via a criminal information.

Such a document typically means a suspect has likely been cooperating with the government. He has been released on bail.

In addition, authorities announced charges against five other suspected members of the hacker group. One was arrested in Chicago yesterday, and one in Ireland early on Tuesday.

LulzSec, an underground group also known as Lulz Security, along with fellow hacking group Anonymous have taken credit for carrying out a number of hacking actions against companies and institutions including the CIA, Britain’s Serious Organized Crime Agency, Japan’s Sony Corp and Mexican government websites.

A lawyer for Monsegur, Peggy Cross, did not immediately return a call seeking comment on the charges.

A spokesman for Irish police said one of the suspects had been arrested and was being held in Terenure, a middle-class suburb of Dublin.

Last summer, as part of a coordinated law enforcement raid on the group, British police arrested another suspected member of LulzSec who went by the nickname “Topiary.”

Jake Davis, a teenager, was charged with computer attacks on Sony, UK crime and health authorities, and Rupert Murdoch’s UK newspaper arm News International.

Davis is believed to have controlled the main Twitter account of Lulz Security, which the group used to publish data obtained by hacking into corporate and government networks.

LulzSec and its parent group Anonymous, loose online collectives of activists, have attracted widespread global media coverage for their stunts. LulzSec has more than 350,000 followers on Twitter.

Last month, the activist group Anonymous published a recording of a confidential call between FBI agents and London detectives in which the law-enforcement agents discuss action they are taking against hacking.