The retailer, Boathouse Row Entertainment Inc., refused to cooperate when staffers at Microsoft's LinkExchange unit asked for details about the ads in order to remove them from the LinkExchange banner ad-swapping network, Microsoft officials said. After being informed about the offending ads by Boathouse Row in April, LinkExchange officials responded that month, asking for details on where the ads had appeared, said Microsoft senior corporate attorney Steve Aeschbacher in an interview Tuesday. "But they told us their lawyers had said it was not in their best interests to supply us with that information," according to Aeschbacher. Boathouse Row, a California.-based seller of official American National Football League cheerleader posters and calendars, and its founder, Sean Patrick Dunn, allege in the suit that within 30 days of joining the LinkExchange network, banner ads for porn sites began appearing on Boathouse Row pages. The ads -- some of which allegedly led viewers to sites featuring child pornography -- appeared on Boathouse Row pages devoted to the Oakland Raiders cheerleaders, according to that company's attorney. When the Raiders organisation discovered the offending banner ads, it amended its contract for Boathouse Row to sell its merchandise, according to the lawsuit. "There was some pretty nasty stuff" on the sites linked to the Boathouse Row pages from the ads, said Mark Goodman of the San Francisco law firm Barger & Wolen LLP, in an interview Monday. The suit was filed in the Superior Court of California in San Francisco. While acknowledging the possibility of some offending materials making their way into the network, LinkExchange takes every possible step to remove the materials as soon as they are found, officials said. "We have a clear and strict policy against pornography on our network," said Deborah Whitman, vice president of marketing and member services at LinkExchange, in an interview Tuesday. Some 1,000 sites and 1,000 banner ads in the free promotional network are reviewed each day by three full-time and six part-time workers to ensure that they comply with the company's terms of service, Whitman said. The Boathouse Row suit marks the first time the banner ad network has been sued over its content, Whitman and Aeschbacher said. Goodman said Monday the lawsuit could "ultimately turn into a multimillion-dollar claim." LinkExchange, bought by Microsoft in November 1998, allows customers to place free banner ads on LinkExchange network member sites in exchange for accepting member ads on their own sites. The service is billed as a no-cost way for small businesses to build Web traffic. LinkExchange's terms of service expressly prohibit ads for pornographic or racist sites, or sites "promoting illegal activity," from being part of the network. But the Oakland Raiders cheerleader organization was dismayed to find that porn ads originating from LinkExchange had found their way onto their pages on the Boathouse Row site, Goodman said. "The Oakland Raiders complained that the defendants' banner advertisements had associated their professional football team and its cheerleading squad with pornographic and illegal material," Boathouse's complaint states. Boathouse Row's attorney maintained LinkExchange initially denied that porn ads could be part of the network, but eventually conceded the error and said they could not be held responsible. The lawsuit seeks financial restitution for the amended Oakland Raiders contract, along with punitive damages.