When the Federal Trade Commission launched its antitrust inquiry into Google in late June, it notified the company that the investigation would delve into business practices in areas including search and advertising. And that appears to remain the case. But it turns out that the FTC is also looking into issues related to Google’s booming Android smartphone operating system.

That’s the word from the Wall Street Journal this afternoon. The paper quotes anonymous sources who say investigators “have been asking whether Google prevents smartphone manufacturers that use its Android operating system from using competitors’ services.”

It’s an interesting development given the quick rise of Android, now accounting for nearly 40 percent of U.S. smartphone usage.

Meanwhile, Google’s share of the U.S. Internet search market remains above 65 percent, according to numbers released today by the comScore Networks research firm.

Google responded to the WSJ by reiterating that it’s happy to answer the FTC’s questions, and it recognizes that “with success comes scrutiny.”

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