Apple is one of several handset makers that have reportedly been subpoenaed as part of the Federal Trade Commission’s antitrust probe into Google.

According to Bloomberg, two unnamed “people familiar with the matter” have said that the agency is seeking answers about how Google’s search engine is used on the iPhone and iPad. The request is reportedly asking for documentation including the deal that made Google the preferred search engine on iOS devices.

The FTC declined to comment on the report. Apple and Google also both declined comment.

Such a request would indicate that the agency is looking more closely at the way Google runs its search business, and whether these kinds of agreements could be viewed as anti-competitive.

Washington has been casting a more critical eye on the technology juggernaut, The Washington Post has reported, with Congress grilling Google chairman Eric Schmidt in a September antitrust hearing and federal regulators recently examining whether the companies social modifications to search were stifling competiton.

According to a recent survey from the Pew Internet and American Life Project, 83 percent of U.S. search engine users prefer to conduct their searches on Google.

Google is also the preferred maps provider for the iPad, though many tech bloggers pointed out that Apple neatly skirted showcasing Google Maps in its iPhoto demo last week. Instead, the iPhoto app is using data from OpenStreetMap, a non-profit mapping group that crowd-sources its information. A blog post from the foundation confirmed that Apple had opted to use its data for the iPhoto app instead of Google Maps.

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