Apple, the darling of the consumer electronics industry and self-styled underdog fighting the all-powerful Microsoft, is — for the first time — facing regulatory scrutiny for alleged monopolistic practices.

The US Federal Communications Commission (FCC) has written to Apple, Google and AT&T, Apple’s exclusive carrier in the United States for the iPhone, after Apple refused to allow an application for the iPhone from Google.

The FCC has also demanded details of which other applications have been refused by Apple for the iPhone, and why.

At the heart of the problem is Apple’s App Store, an online shop for hundreds of thousands of software applications that run on the iPhone. Applications for everything from maps to stock prices to digital glasses of beer have been downloaded in their millions by iPhone users — but the applications are software created by independent developers, not by Apple. It has created an App Store approval process to regulate the custom-built software and their content before they are allowed in.

From the start, a year ago, there have been complaints about delays and inconsistent decisions. Then last month Apple refused to allow the Google Voice mobile app, which allows users to send and receive text messages via a single Google Voicephone number. It is available for other phones.

David Coursey, an analyst who has been following Apple for 20 years, said: “Apple has never been looked at seriously by regulators before. Apple was always the underdog. Now Apple has become a dominant force in the market and competitors are showing up in the smartphone space. The idea is that someone might say ‘let’s look at the whole thing’ isn’t impossible.”

Launching its inquiry into the App Store, Julius Genachowski, the FCC chairman, said that the commission had “a mission to foster a competitive wireless marketplace, protect and empower consumers, and promote innovation and investment”.

Apple, AT&T and Google are due to respond formally to the FCC this week. Apple declined to comment on its decision to ban the Google Voice application.

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