"The club would like to offer its sincere condolences to the family of the player.
Benitez had recently joined the club from Club America for three seasons.
The player participated for the first time with the team during yesterday's match against Qatar Sports Club in the Sheikh Jassem Cup without complaining of any health problems.
His sudden departure is a big shock for each member of the technical and administrative staff.
He was a player that over the short period he was here was regarded for his high moral character."
More top news
A pensioner who made neighbours' lives a misery, including displaying images of Miss Piggy to torment an overweight woman, has been jailed.
A newly promoted police officer caused a sensation with local women on Facebook
Headteachers could strike in protest at government plans to force schools to become academies