Speaking at a Forum Europa breakfast held at the Valencia campus of the Menéndez Pelayo International University, Montserrat Gomendio asked if Spain should continue with its current grants system or adopt a UK-style system.
Under the new plan, students would have to pay back their university fees "in easy, interest-free payments" once they were earning over €21,000 per year, according to Spanish daily ABC.
She noted that the university system had grown exponentially in recent years, at a "very high" cost.
"It is not a question of free or not free," she said, "but of who pays, how, and when."
"The Ministry has not yet taken any decision in this respect but it is one of the questions we must consider," she added.