Minchev, 19, is considered one of Bulgaria’s best talents and plays for top-flight club Cherno More.
He has scored six goals in 21 appearances for Cherno in the efbet Liga, while winning four caps for Bulgaria.
Serie B side Empoli had a January loan bid rejected for Minchev, and bigger clubs are now interested.
Torino and Scottish champions Celtic are both considering the teenage forward to bolster their attacking ranks.
Belgian giants Anderlecht could also enter the running for Minchev as they consider forward options.