Diop, 21, made his senior debut in Ligue 1 back in 2015 and amassed 85 appearances for Toulouse while being named club captain as a teenager for his final season at his home-town club.
He then went on to become West Ham's club record signing when the Premier League side paid £22m for him during the off-season.
And since breaking into Manuel Pellegrini's starting XI, the towering defender has drawn plenty of plaudits for his early displays in the English top-flight.
This brought further interest in his international future as he was born in France to a Moroccan mother and Senegalese father and has played for France at youth level - while his grandfather Labysse, became the first Senegalese to play in Ligue 1 when he signed for Bordeaux in the 1970's.
"I have always said that I will only play for France and no one else," Diop told ladepeche.fr.
"Whether I am selected or even if I am never selected with the A's, I will not play for another team.
"I was born in France. It's in France that I have everything. So I do not see why I would play for another nation."
Diop scored France's final goal as they beat Italy 4-0 to win the 2016 European Under-19 Championship.