Cristobal Pera, editorial director of Penguin Random House Mexico, said that Garcia Marquez's family has not yet decided whether to allow the book to come out posthumously, or which publishing house would get the rights. Garcia Marquez died at his Mexico City home on April 17.
The manuscript has a working title of "We'll See Each Other in August," ("En Agosto Nos Vemos").
An excerpt of the manuscript published in Spain's La Vanguardia newspaper contains what appears to be an opening chapter, describing a trip taken by a 50-ish married woman who visits her mother's grave on a tropical island every year. In the chapter, she has an affair with a man of about the same age at the hotel where she stays.
The erotic tone of the work is heightened by the island's tropical charm, with deftly drawn touches of the heat, the landscape, music, and local inhabitants.
The manuscript apparently dates to about the time Garcia Marquez was writing his last novel, "Memories of my Melancholy Whores," which was published in 2004, and deals with similar themes of forms of love; Garcia Marquez, beset by a failing memory, apparently did not write much in recent years.
"'I'm not going to write anymore," Mexican writer Homero Aridjis recalls Garcia Marquez telling him in 2005.
Garcia Marquez biographer Gerald Martin said the manuscript apparently started as a short story.
"This has come as a surprise to me. The last time I talked to Gabo about this story it was a stand-alone which he was going to include in a book with three similar but independent stories," Martin said.
"Now they're talking about a series of episodes in which the woman turns up and has a different adventure each year," he wrote in an email. "Obviously it makes sense and presumably Gabo really did play with it, presumably some years ago."
Colombia's Culture Ministry said Tuesday it is creating a $100,000 annual literary prize that will bear Garcia Marquez's name, for the best short story in Spanish.
AP Writer Frank Bajak in Lima, Peru and Mark Stevenson in Mexico City contributed to this report.