1-800 Contacts Inc., the Draper, Utah-based online retailer of contact lenses, sued competitor Drugstore.com Inc. for placing Internet ads so they appear when consumers look up "1-800 Contacts" in a search engine.

Drugstore.com's Vision Direct unit is infringing a trademark because its online ads show up when shoppers search for 1-800 Contacts' trademarked name, the company said in a suit filed yesterday in federal court in Salt Lake City.

"Defendants' actions steal customers from plaintiff, erode the effectiveness of plaintiff's Internet sales and marketing operations, and disrupt plaintiff's business," 1-800 Contacts said in the complaint.

The ads, known as "sponsored links" on Google Inc.'s search-results pages, violate a 2004 settlement agreement between 1-800 Contacts and Vision Direct, according to the suit. The deal was reached to end an infringement lawsuit that was filed over the same ads before Drugstore.com's acquisition of Vision Direct in 2003.

Drugstore.com, based in Bellevue, Washington, is an online retailer of health and pharmacy products. 1-800 Contacts filed a similar suit against competitor Lens.com Inc. in August. That case is pending in the same court.

Google's AdWords program, which allows companies to display ads next to search results for competitors, has triggered several lawsuits. The biggest, filed against Google by auto insurer Geico Corp., was settled in September 2005.