NEW YORK (Frankfurt: A0DKRK - news) , Jan 19 (Reuters) - Sprint Nextel (NYSE: S - news) , DirecTV, T-Mobile USA and others asked the U.S. telecommunications regulator to seek and disclose more information on Verizon Wireless' proposed purchase of wireless airwaves from cable companies.

Verizon Wireless has announced it would spend almost $4 billion to buy wireless spectrum from its cable rivals as part of broader agreements that include formation of a joint venture and cable operator resale of its wireless services.

Spectrum (Berlin: 7S9.BE - news) sales need approval from the Federal Communications Commission because it regulates the transfer of a spectrum license.

But since the Verizon Wireless agreement with cable operators including Comcast (NYSE: CCS - news) and Time Warner Cable (NYSE: TWC - news) is much broader than a spectrum sale, its rivals and consumer advocacy groups are asking for details of other elements of the deal.

"Without the ability to review the larger transaction in its entirety, it is impossible to assess whether there will be public interest harms associated with this proposed transfer," the group wrote in a letter to FCC Chairman Julius Genachowski.

The group ask Genachowski for help in "acquiring the information necessary to adequately evaluate the proposed transactions and relationships" so that it could give the FCC its comments on the deal.

The FCC has a formal process which takes public comments from rivals and other interested parties into account when reviewing telecommunications deals. Sprint, the No 3 U.S. mobile provider, was the more vocal opponent of a failed plan last year by AT&T Inc to buy No. 4 U.S. mobile provider T-Mobile USA, a unit of Deutsche Telekom (Xetra: 555750 - news) .

The Department of Justice is also examining the cable deal with Verizon Wireless, a venture of Verizon Communications and Vodafone Group Plc.

(Reporting By Sinead Carew)