Hackers have breached the mailing list of the Congressional Budget Office (CBO), according to the agency.

"There was limited breach of our list server that has since been patched and closed," said Melissa Merson, a CBO spokeswoman. "When people access a federal government computer, that's considered a possible criminal violation. So we've referred the matter to the appropriate law enforcement authorities, and it's under investigation."

Merson said the hackers sent out a message purporting to be a CBO email, but she declined to offer any details because the matter had been referred to law enforcement officials for investigation.

However, according to a report in The Washington Post, the CBO recently sent out an email warning that someone was using the agency's mailing list to try to get private information about those on the list.

"Several people have reported receiving an email message that appears to have been sent from the Congressional Budget Office," the email said, according to the Post. "The message is actually Phish and appears to come from outside the US. We are not sure how many people received the message or how the address list was obtained, [but] if you received an email message from: 'Budget Office ' and using a subject line that says 'The Budget and Economic Outlook Fiscal Years 2007 to 2016,' then please delete it. Also, DO NOT click on the link at the bottom of the message. It could possibly infect your computer with spyware or a virus.'"