Like music fans with Napster, tens of millions of Internet users have transformed the club and community sections of Yahoo and Microsoft's MSN networks into havens for swapping hard-core images.

Several religious and civic groups say these sites--unlike ones offered by rivals--make it easy for children to view explicit material. Neither Yahoo nor MSN requires physical proof of age or a credit card number to enter adult areas. Microsoft and Yahoo officials acknowledge that some of their more than 70 million members have created virtual red-light districts, just as some have built communities for snowboarding and needlepoint. But the companies say their role is not to play morality police on the Net.

"While we provide adult sections within some community services to age-appropriate audiences, we do not condone unlawful content on our network" such as child pornography, said Joanna Stevens, director of Yahoo's corporate communications.

MSN echoed that sentiment. Spokeswoman Sarah Lefko said the service focuses on pulling material that is blatantly illegal, such as child pornography, bestiality and incest.

The approach of MSN and Yahoo contrasts with that of some of its rivals, including America Online. Although the nation's biggest Internet company is well-known for risque chat rooms, AOL prohibits the posting of pornographic images or videos on its service.

Smaller Internet players, such as Terra Lycos, allow users to create adult clubs but have discouraged such activities by making it difficult to find those groups.

Neither Microsoft nor Yahoo will say how many of the clubs and communities on their networks host explicit fare. A search for the word "porn" in MSN's communities area brings up more than 2,700 sites. There are more than 1,700 "Triple X" sites in Yahoo's adult club section, according to a directory of links compiled by one Web site.

An Internet club operates like a virtual bulletin board. Users can chat and share photographs, videos, e-mail addresses and other information.

Finding these gathering spots is fairly simple. On MSN, a user needs only to type erotic words into a search engine that scours through all of the service's online communities.

Yahoo clubs are set apart in an area called "online clubs." Consumers say they find specific adult clubs by word of mouth, on search engines such as Google or in Yahoo's "most popular" list of romance clubs.

Yahoo and MSN have resisted pressure to eliminate sexual content from their networks.

"We've tried to talk to these technology companies, and they just refuse to listen," said Patrick Trueman, director of government affairs for the American Family Assn. and former chief of the U.S. Justice Department's Child Exploitation and Obscenity section under then-President George Bush.

Trueman said his group has joined forces with the Family Research Council and the Traditional Values Coalition, as well as Concerned Women for America, a 600,000-member public policy group.

The AFA, which since mid-June has been issuing one news release a week targeting specific Yahoo clubs, says it will present a petition to the company this fall calling for a ban on all adult clubs.

The group also is organizing a boycott of the search engine and its advertisers, including insurance firm State Farm, PC maker Dell Computer Corp. and brokerage giant Fidelity Investments.

Yahoo Cut Off Public Links to Adult Clubs

Yahoo's Stevens said that it is up to consumers to alert the company to problems and that "we have a strong track record of taking appropriate action."

Yahoo has tried to make the clubs less visible. In April, the company altered the directories that users need to navigate the site and cut off public links to its adult clubs.

This has not prevented users from continuing to flock to the clubs. "No one has the right to dictate to another what they can or cannot view or be into," wrote one user to the club Yahoo Petitions, a site created to protest Yahoo's move.

The debate has gotten the attention of the federal government. In June, U.S. Atty. Gen. John Ashcroft told a House Judiciary Committee that he was concerned about obscenity on the Internet and "concerned about obscenity as it relates to our children." Justice officials have since said they are focusing on child pornography and pedophile rings.

Consumers who frequent the adult clubs say Microsoft and Yahoo have made it easier for the more than 100 million people worldwide who use their sites each month to find porn images for free.

The two services also are familiar turf for children, many of whom have grown up searching the Yahoo directory for help with their homework, meeting friends on Yahooligans and playing games and watching movie clips on MSN.

Yahoo executives said consumers can access the site's adult area only if, when signing up to join the club, they say they're 18 or older. Microsoft follows a similar approach: Before entering such areas, users see a warning page and click on a button to agree that they are older than 18 and want to see "adult" content.

However, consumers do not need to provide proof of their age, such as providing a credit card number.

Although Yahoo and MSN's clubs are not explicit commercial ventures, the companies are passively profiting from these areas. What they get is one of the most precious of modern commodities: loyal customers, brand recognition and millions of eyeballs that can translate into higher advertising rates and increased sales.

"Either these companies should admit they're profiting off of pornography and create a way to truly keep kids out, or they should stop what they're doing," said the AFA's Trueman.

Yahoo is no stranger to controversy when it comes to content on its service.

The Sunnyvale, Calif., company is embroiled in a legal fight with two French groups over a site that hosts auctions offering Nazi memorabilia such as medallions, flags and swords.

The two groups--the Union of French Law Students and the International League Against Racism and Anti-Semitism--accused Yahoo of violating a French law that makes it illegal to sell or exhibit anything that incites racism. Although the data are stored on computers in the U.S., a French judge last fall ordered Yahoo to block French residents from viewing Nazi memorabilia in its online auctions.

Yahoo pulled the Nazi material from its auctions, but the company filed a lawsuit in San Jose against the French groups late last year, asking a U.S. District Court to declare French laws unenforceable in the United States.

The American judge is expected soon to rule on the case, which is being closely watched by free-speech advocates.

"If Yahoo loses, companies could be subjected to endless grass-roots tyranny, and thousands municipalities in the U.S. alone could demand that online companies customize their services in thousands of variations," said Adam Thierer, director of telecommunications studies for the Cato Institute, a political think tank in Washington.

Online Adult Industry Opposes Portals' Clubs

Meanwhile, Yahoo also is facing opposition from the adult-entertainment industry. It fears that MSN's and Yahoo's adult clubs are starting to lure consumers away from for-pay porn services.

Often, these commercial Web sites promise free explicit fare, then bombard viewers with advertisements and requests for payment.

"These clubs have more extreme stuff than anyone in the legitimate side of this business would ever do," said Scott Schalin, chief executive of IGallery Inc., operators of commercial porn sites such as Cafe Flesh. "There's no way we can compete against this."

The online adult industry saw sales begin to slump this year. Part of the problem is an industrywide change in how credit card orders are processed, a strategy to cut down on fraud.

But some fear the downturn will continue. New Frontier Media Inc., one of the few publicly traded adult companies, reported net income of $19.9 million from online subscriptions in fiscal 2001, only a shade above the $19.4 million total for fiscal 2000. The results were disappointing, considering revenue increased 67% the previous year.

"In terms of free content, the portals dominate the delivery," said Mark Kreloff, chief executive of New Frontier, which distributes both hard-core porn and softer adult content via the Net and pay-per-view television. "Clearly, that's our biggest competitive threat."

Microsoft and Yahoo created the clubs in the heady days of the dot-com boom as a way of attracting online visitors and keeping them there. The online giants were following in the footsteps of competitors such as GeoCities, then based in Marina del Rey.

In 1999, Yahoo bought GeoCities in an all-stock deal valued at nearly $1.6 billion. At the time, Yahoo officials were betting that they could turn those communities into shoppers.

Consumers flocked to these virtual gathering places, creating groups dedicated to everything from Stalin's politics to stamp-collecting to, inevitably, sex.

"It's a really touchy subject because they spent billions of dollars developing these brands," said John Corcoran, executive director for the Internet and new-media group at CIBC World Markets. "Obviously, they don't want 4-year-olds looking at bestiality. The fear is that if they got rid of the porn, then they'd be going down a slippery slope. Where do you draw the line?"