Target data breach being probed by Justice Department, confirms US Attorney General

Testifying at a U.S. Senate hearing, Holder said the department will seek not only to find the perpetrators of the breach but also "any individuals and groups who exploit that data via credit card fraud."

Target has said a breach of its networks during the busy holiday shopping period resulted in the theft of about 40 million credit and debit card records and 70 million other records with customer information such as addresses and telephone numbers.

(Also see: Target says data breach affected 70 million customers)

The United States Secret Service usually takes the lead in credit card breach investigations for the federal government.

In his statement to senators, Holder said the department took reports of data breaches seriously.

"While we generally do not discuss specific matters under investigation, I can confirm the Department is investigating the breach involving the U.S. retailer, Target," he said.

Reuters reported on January 23 that the U.S. Federal Bureau of Investigation has warned U.S. retailers to prepare for more cyber-attacks after discovering about 20 hacking cases in the past year that involved the same kind of malicious software used against Target Corp in the holiday shopping season.

(Also see: FBI warns US retailers to expect more credit card breaches)

© Thomson Reuters 2014