WASHINGTON The television network CNN is being sued by a producer it fired over a story alleging that U.S. forces used nerve gas in the hunt for American defectors during the Vietnam War. In a lawsuit filed Friday in the district of Columbia superior court, April Oliver claimed CNN wrongfully dismissed her last year and said the Cable News Network based its decision ``primarily on business and public relations concerns.'' A CNN spokeswoman said the network does not comment on ``matters pertaining to litigation.'' (AP)