NEW YORK (AP) - A national advertising watchdog is asking Sprint Nextel Corp. to drop its ads calling itself "America's most dependable 3G network."

The National Advertising Division of the Council of Better Business Bureaus made the recommendation following a challenge to Sprint's ads by rival Verizon Wireless.

The division said the most recent tests by the researcher Nielsen Co. showed Verizon had fewer calls blocked or dropped than Sprint. Sprint argued that reviewers should look at more than one set of tests to avoid one-time events like weather or bad cell towers.

Sprint, based in Overland Park, Kan., stands by its claims and says it will appeal to the National Advertising Review Board.

AT&T Inc. recently challenged Verizon Wireless over ads claiming it has wider coverage than AT&T.

Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.