Eleven people, including a U.S. Secret Service informant, have been charged in connection with the hacking of nine major retailers and the theft and sale of more than 41 million credit and debit card numbers, the Justice Department announced Tuesday.

The data breach is believed to be the largest hacking and identity theft case ever prosecuted by the Department of Justice, which said the suspects were charged with conspiracy, computer intrusion, fraud and identity theft.

Three of those charged are U.S. citizens while the others are from places such as Estonia, Ukraine, Belarus and China.

The indictment returned Tuesday by a federal grand jury in Boston alleges that the suspects hacked into the wireless computer networks of retailers including TJX Cos., BJ’s Wholesale Club, OfficeMax, Boston Market, Barnes & Noble, Sports Authority, Forever 21 and DSW and set up programs that captured card numbers, passwords and account information.

“They used sophisticated computer hacking techniques that would allow them to breach security systems and install programs that gathered enormous quantities of personal financial data, which they then allegedly either sold to others or used themselves,” Attorney General Michael Mukasey said at a news conference. “And in total, they caused widespread losses by banks, retailers, and consumers.”

Mukasey called the total dollar amount of the alleged theft “impossible to quantify at this point.” U.S. Attorney Michael J. Sullivan said that while most of the victims were in the United States, officials still haven’t identified all the people who had a card number stolen.

“I suspect that a lot of people are unaware that their identifying information has been compromised,” he said.