Gawker Media LLC said the Federal Bureau of Investigation asked it to retain documents as part of a probe into the exposure of email addresses belonging to iPad owners, the second time the blog publisher has been in a legal spotlight over a big news story it wrote involving Apple Inc.

The New York-based media company said Friday it had been contacted by the FBI to preserve the information, but Gawker Media said it doesn't believe it is a target of the probe. The FBI said Thursday it opened a probe but hasn't said what it...