The DOJ declined to comment on whether it's investigating the breach at Target, the nation's second largest discounter.
Target also said that it's teaming up with the U.S. Secret Service in its own investigation. Target said the Secret Service has asked the company not to share many of the details of the probe.
Additionally, Target said that it held a conference call with the state attorneys general on Monday.
The investigations and the call come after Target said last week that data connected to about 40 million credit and debit card accounts was stolen starting over the Thanksgiving weekend.