From Conquerors by Roger Crowley,
A second detachment of five ships under Estevao de Gama followed on April 1. The amplified expedition included a number of observers who would write eyewitness accounts. Some were anonymous; others identified themselves. They included a Portuguese clerk, Tome Lopes, and an Italian commercial agent, Matteo de Bergamo, both in Estevao's squadron, who recorded the progress of an expedition that...
Since information about the sea routes was crucial at the time and there was essentially a "covert commercial war between Venice and Portugal", why would the Portuguese have allowed an Italian on board?