U.S. antitrust regulators have given clearance to a proposed $483 million merger between Sprint Nextel Corp. (S) and Virgin Mobile USA Inc. (VM), according to a notice released Monday by the Federal Trade Commission.

Sprint announced in July it would acquire Virgin. In buying Virgin Mobile, Sprint is taking over one of its wireless resellers and gaining a pay-as-you-go option that rounds out its low-end offering.

Sprint has struggled to keep its more lucrative contract subscribers and has turned to its Boost Mobile unit, which provides a cheaper service without contracts, to shore up defections.

As consumers tighten their belts during the economic slowdown, more people are gravitating toward cheaper prepaid plans that don't require lengthy service contracts.

The deal also will be subject to review by the Federal Communications Commission.

Virgin Mobile holds a small number of international licenses that need to be transferred to Sprint to complete the deal, giving the FCC the jurisdiction to review it.

Sprint and Virgin have filed an application with the FCC and expect the commission to seek public comment on the transfer within the next few weeks.

Sprint spokesman Scott Sloat said applications of this type are typically processed under an FCC-streamlined procedure that would approve the transfer automatically after the comment period.

An FCC official said the agency hasn't yet been determined how the Sprint/Virgin merger will be assessed.

The FCC last year cleared Sprint's purchase of Clearwire Corp. (CLWR).

-By Fawn Johnson, Dow Jones Newswires; 202-862-9263; fawn.johnson@dowjones.com