WASHINGTON â€"  Mitt Romney's campaign is investigating whether his private email was hacked after a tipster claimed he had accessed the presumptive GOP nominee's Hotmail account by answering a simple security question.

A raft of old emails from Romney's time as Massachusetts governor was released Tuesday by The Wall Street Journal, revealing he communicated with staff using the email address "mittromney@hotmail.com."

Later Tuesday, Gawker reported that an anonymous hacker had signed into the Hotmail account after guessing the answer to a security question about one of Romney's pets.

"I hacked in after finding the answer to the security question, 'What is your favorite pet?'" the hacker wrote in an email to Gawker.

"This is all I have gotten into. I have nothing to do with Anonymous and have never done anything like this before," the person added, referring to the global group of computer hackers.

The hacker revealed the answer to the question and the new password they created to Gawker, but the website did not publish either.

Romney's campaign said it was investigating the matter.

"The proper authorities are investigating this crime and we will have no further comment on it," said the campaign's communication director, Gail Gitcho, in a statement to Politico.

Suggestions were quickly made that the answer to the Romney pet question may have been "Seamus," the Irish setter that was at the center of an infamous family vacation.

Seamus became ill with diarrhea after being strapped to the family's station wagon on a 1983 trip from Boston to Canada. The tale has dogged Romney for years and has been raised again during this campaign, with critics calling it an example of the presumptive Republican nominee's uncaring attitude.