Organizers of two of the biggest comic-book conventions in the country are clashing over their names.

A lawyer for San Diego Comic-Con has issued a cease-and-desist letter to organizers of Utah's Salt Lake Comic Con demanding them to drop "Comic Con" from the name.

"Attendees, exhibitors and fans seeing use of 'Comic Con' in connection with your convention will incorrectly assume that your convention is in some way affiliated with (the San Diego convention)," reads the letter dated Friday.

San Diego holds the nation's biggest comic-book convention while Salt Lake City hosts the third-biggest one. Organizers say the events feature the best in movies, television shows, gaming, sci-fi/fantasy and comic books. Many attendees dress up as their favorite characters.

The letter further states that San Diego organizers own the trademark for the use of "Comic Con" and are aware of "multiple instances" where individuals believed the two gatherings were affiliated because of the name.

The letter notes a car was used to promote the Salt Lake City convention around the site of this year's San Diego Comic-Con. The car featured the Salt Lake Comic Con name and dates. "Your use (of the car) ... is clearly intended to confuse Comic-Con attendees, exhibitors and fans," the letter states.

The letter calls for a response by Salt Lake City organizers by Aug. 6.

Salt Lake Comic Con co-founder Dan Farr called the demand baseless.

"We're puzzled why Salt Lake Comic Con was apparently singled out amongst the hundreds of Comic Cons around the country and the world," Farr said in a statement. "We intend to vigorously defend ourselves from this frivolous action."

San Diego Comic-Con tried and failed to trademark "Comic Con" in 1995, said Bryan Brandenburg, co-founder of the Utah convention.

Salt Lake Comic Con set a record for the biggest turnout for a new comic-book convention last year with an estimated 72,000 people.