"He is a terrific player and I don't think we will keep him at the end of the season as I feel he will go to a big club then," said the City boss.
"The deal we have is not tight and other teams are sure to nip in."
Van Buyten explained: "I left l'OM because the club had financial problems but I am only loaned in England.
"The Marseille president has already telephoned me to say he hoped to re-examine me in three months.
"Moreover, if the club had wanted to definitively transfer me to Manchester City, I would not have accepted. Currently, I am simply enjoying the experience."