William Branigin, in "Mexicans Let In on Presidential Race" {Aug. 30}, refers to the infighting surrounding the Mexican presidential succession and writes:

"Suspicions of such maneuvering already have cropped up with the recent publication of two books. One, a political thriller that was seen as disparaging the country's powerful oil workers' union, reportedly prompted the union to blame Budget and Planning Secretary Salinas and commission a book in retaliation, a diplomat said. The second book, entitled 'A Killer Can Become President,' recounts an incident in which Salinas, as a child, accidentally shot to death a family maid."

First, in relation to this tragic incident, Carlos Salinas de Gortari, who was three years old at the time, was only an eyewitness.

Second, by alluding to the latter book and to the incident, The Post not only hurts the reputation of a high-ranking Mexican official but also, without having all the information, gives credence to a libel that has been repudiated. Legal proceedings against the book's authors have already condemned the publication of the book.

No one would seriously suggest that a three-year-old child, who was only an eyewitness, was morally, psychologically or legally responsible for such an unfortunate event.

ADRIANA GOMEZ Head of the Foreign Press Bureau Ministry of Planning and Budget of Mexico Mexico City