WASHINGTON – Verizon Wireless said it would sell billions of dollars worth of prime airwaves if regulators approve its planned purchases of new chunks of spectrum that come mainly from large cable companies.

Verizon paid about $4.7 billion in 2008 to outbid Google in a government auction of coveted airwaves in the 700 megahertz band.

The wireless giant’s announcement Wednesday was designed to reduce criticism from competitors and public interest groups about its purchase of spectrum from a consortium of Comcast Corp., Time Warner Cable Inc. and Bright House Networks, as well as other acquisitions of spectrum from Cox Communications Inc. and Leap Wireless International Inc.

“Since wireless operators, large and small, have expressed concern about the availability of high-quality spectrum, we believe our 700 megahertz licenses will be attractive to a wide range of buyers,” said Molly Feldman, vice president of business development at Verizon Wireless.

The Federal Communications Commission and the Department of Justice are reviewing Verizon’s new spectrum purchases. The company agreed in December to pay $3.6 billion for the airwaves from the cable consortium, which had planned to use them to enter the wireless business.

Verizon also agreed to buy airwaves from Cox, a former member of the consortium, for $315 million and wants approval to swap some spectrum with Leap.

Public Knowledge, a consumer advocacy group, said it still opposed Verizon’s acquisitions and doubted that the company’s offer to sell other spectrum would lead to more wireless competition.

“Verizon is trying to use the mere offer of a spectrum sale to tempt the FCC and the Justice Department into approving the deal with the cable companies, and the agencies should resist the temptation,” said Harold Feld, legal director of Public Knowledge.

“Recent history of such spectrum sell-offs shows that when Verizon and AT&T sell off spectrum, it’s Verizon who buys AT&T’s, and vice versa,” he said. “Having AT&T buy Verizon spectrum in this instance would do nothing to change to help consumers.”

Regulators could require Verizon to sell some of its 700 megahertz airwaves as a contingency for approving the deals, and could bar large participants such as AT&T from acquiring the spectrum.

Verizon Wireless, a joint venture between Verizon Communications Inc. and Vodafone Group PLC, said it expected to get approval for its acquisitions by midsummer.