The 15-year-old attacking midfielder has emerged as one of Germany's promising young talents, having already progressed to Frankfurt's U19 setup despite his age.
According to Fichajes, citing Sky Sport, both Spanish giants are monitoring Ilicević closely as they consider moves for the teenager.
“Real Madrid, FC Barcelona, Manchester City, AC Milan and Inter Milan are closely monitoring the progress of this promising young player from Eintracht Frankfurt.”
His technical quality, creativity and eye for goal have attracted attention across Germany, with Bayern Munich reportedly tracking his development for several years.
Frankfurt remain determined to retain their highly-rated prospect and are expected to resist approaches as Europe's biggest clubs continue monitoring his progress and long-term development.