A retailer of promotional goods for the American National Football League cheerleader squads on Monday filed suit against LinkExchange Inc., alleging the Microsoft-owned banner ad-swapping network posted ads for pornographic Web sites on some of its Web pages. Boathouse Row Entertainment Inc., a California-based seller of official NFL 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 the 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. Goodman said it was difficult to put a dollar amount on the amount of damages sought. "If the practice [of linking to porn sites] is found to be very extensive, it could ultimately turn into a multimillion-dollar claim," he said. Microsoft spokesman Jim Cullinan said late Monday that company officials could not comment on the case since they had not yet seen the lawsuit. LinkExchange, acquired 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 organisation 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. "Furthermore, the defendants' actions caused professional football fans, without consideration for age or consent, to be exposed to nude images and lewd sexual and illegal material, including child pornography." When Boathouse Row officials contacted LinkExchange about the problem, they were first told "it was not possible" for porn ads to make their way into the network, Goodman said. But eventually, when shown screen captures proving the offending ads had been placed, LinkExchange acknowledged the error but said it could not be held responsible, the attorney said. "They basically said they can't be held responsible for sites that change their topic or focus after the initial evaluation" to determine whether they are suitable to be included in the LinkExchange network, Goodman said. The lawsuit seeks financial restitution for the amended Oakland Raiders contract, along with punitive damages.