Attacking an increasingly popular Internet business practice, a consumer watchdog group Monday filed a complaint with the Federal Trade Commission, asserting that many online search engines are concealing the impact special fees have on search results by Internet users. Commercial Alert, a 3-year-old group founded by consumer activist Ralph Nader, asked the FTC to investigate whether eight of the Web's largest search engines are violating federal laws against deceptive advertising. The group said that the search engines are abandoning objective formulas to determine the order of their listed results and selling the top spots to the highest bidders without making adequate disclosures to Web surfers. The complaint touches a hot-button issue affecting tens of mil-lions of people who submit search queries each day. With more than 2 billion pages and more than 14 billion hyperlinks on the Web, search requests rank as the second most popular online activity after E-mail. The eight search engines named in Commercial Alerts complaint are: MSN, owned by Microsoft Netscape, owned by AOL Time Warner Directhit, owned by Ask Jeeves HotBot and Lycos, both owned by Term Lycos AhaVista, owned by CMGI LookSmart, owned by LookSmart and iWon, owned by a privately held company operating under the same name. 'Portland, Ore-based Commercial Alert could have named more search engines in its complaint, but focused on the biggest sites that are auctioning off spots in their results,' said Gary Ruskin, the group's executive director. 'Search engines have be-come central in the quest for learning and knowledge in our society. The ability to skew the results in favor of hucksters without telling consumers is a serious problem,' Ruskin said. By late Monday afternoon, three of the search engines had responded to The Associated Press' inquiries about the complaint. Two, LookSmart and AltaVista, denied the charges. Microsoft spokesman Matt Pilla said MSN is delivering 'compelling search results that people want.' The FTC had no comment about the complaint Monday. The complaint takes aim at the new business plans embraced by more search engines as they try to cash in on their pivotal role as Web guides and reverse a steady stream of losses. To boost revenue, search engines in the past year have been accepting payments from businesses interested in receiving a higher ranking in certain categories or ensuring that their sites are reviewed more frequently. The consumer group complained about ______ .