Donnarumma became the youngest goalkeeper ever to debut in Serie A at the age of 16, and has since become Milan's undisputed number one despite only turning 18 in February.
The teenager, who stands at 6'5", also became Italy's youngest ever stopper when he made his international debut in last September's friendly with France.
Raiola has denied that he has held talks with any particular club, but the agent has insisted that his client 'is ready to play for Real Madrid'.
"Offers from other teams? The ones being spoken of, they have been looking for him since he was 14, so if he wanted to leave, he could have done it before. We do not have an agreement with any team. Is Donnarumma ready to play for [Real] Madrid? He was born ready," Raiola told reporters.
Donnarumma is currently with the Italy squad at the Under-21 European Championships in Poland.