By John Poirier

WASHINGTON (Reuters) - The U.S. Federal Communications Commission launched an inquiry on Thursday to examine the state of competition in the wireless industry, taking a step that could lead to probes of other sectors.

The FCC issued a notice of inquiry as part of a congressionally mandated annual assessment of the industry which is dominated by Verizon Wireless, AT&T Inc, Sprint Nextel Corp and T-Mobile, a unit of Deutsche Telekom AG.

Verizon Wireless is a joint venture between Verizon Communications Inc and Vodafone Group Plc.

The inquiry comes as the FCC is in the midst of examining exclusive deals between handset makers and carriers, such as Apple Inc's popular iPhone whose sole U.S. service provider is AT&T.

Exclusive deals are common among the biggest carriers but have recently faced strong opposition from rural carriers which say they lack the clout to make deals to carry the most popular phones.

FCC Chairman Julius Genachowski said the agency is seeking data on how competition affects consumers. He also said the wireless inquiry could lay the foundation for future questions in other sectors such as cable and broadband.

"I hope the new wireless competition report will help set a standard for fact-based, analytically deep analysis of the mobile industry," Genachowski, a Democrat, said during an open meeting with a full slate of commissioners.

The five FCC commissioners also voted unanimously in favor of issuing a separate inquiry into how the agency can help spur innovation and investment across the wireless sector focusing on spectrum, networks, devices, applications and business models.

The agency also wants to examine if the current condition in the wireless market allows for new entrants.

The comment period for both initiatives is 30 days along with another 15 days for replies from the FCC.

Both Republican commissioners, Robert McDowell and Meredith Baker, said the comment period is too short to gather data. McDowell also said that competition exists in the wireless industry and prices for wireless services have dropped.

"This investigation is long overdue," said Andrew Jay Schwartzman, president of Media Access Project.

"The country's four major wireless providers have enjoyed the fruits of market power for too many years, at the expense of the public's ability to gain widespread access to low-cost mobile broadband services," Schwartzman said.

The wireless industry's trade group, CTIA, said the industry has the "least concentrated wireless market on the planet."

"The wireless ecosystem -- from carriers to handset manufacturers, to network providers, to operating system providers, to application developers -- is evolving before our eyes and this is not the same market that it was even three years ago," CTIA President Steve Largent said in a statement.

Genachowski, a former tech industry executive and a law school friend of President Barack Obama, has said he wants the agency to focus more on how the agency can empower consumers.

(Reporting by John Poirier, Editing by Maureen Bavdek and Matthew Lewis)