The Azzurri have been warned they face competition for the 19 year-old.
"We are in very advanced negotiations with Napoli for Radosevic, but have not yet reached a conclusion," Hajduk President Martin Brbic told Radio Crc.
"The lad wants to play for Napoli and there is not long before we can conclude the deal. There is not a big gap between offer and demand.
"However, there are other clubs who want Radosevic, including Parma."