According to a report from Bloomberg (via AllThingsD), the U.S. Federal Trade Commission subpoenaed Apple as part of its antitrust investigation of Google. There are not many details currently, but the report claimed the FTC is interested in Apple’s agreement with the company to use Google as its primary default search engine on iOS devices.

The agency’s request for documents includes the agreements that made Google the preferred search engine on Apple’s mobile devices, said the people, who weren’t authorized to speak publicly and declined to be identified. Google rivals such as Microsoft Corp. (MSFT) have criticized these agreements as anticompetitive.

The report claimed the investigation is still focusing on whether Google is “abusing its dominance of Internet search to boost revenue,” but it now included Apple and other unnamed smartphone vendors and carriers in the probe. Apple has used Google as the default search option on iOS devices since the debut of the original iPhone in 2007. Apple also implements Google Maps in iOS, but some speculated Apple is planning to use its own mapping solution after it was discovered the new iPhoto iOS app is using OpenStreetMap data and not Google Maps.

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