Juventus great Alessandro Del Piero said he is stunned by Leonardo Bonucci's reported switch to Serie A rivals AC Milan, adding he thought news of the transfer was a joke.

Speculation is rife that Juventus defender and Italy international Bonucci is closing in on a shock move to Milan, with other reports claiming a rift between him and head coach Massimiliano Allegri.

Bonucci's agent refused to dismiss speculation on Thursday amid reports of a €40million fee for the 30-year-old – also a target for Premier League champions Chelsea and Manchester City – and the news has taken former Juve captain Del Piero by surprise.

"I didn't expect it," Del Piero told Sky Sport Italia.

"It looked like a joke, the news came like a bolt from the blue. It is a very, very amazing deal, I would not have thought about such a thing."

Since moving to Turin from Bari in 2010, Bonucci has helped Juventus to six successive Serie A titles as well as three Coppa Italia crowns and as many Supercoppa Italiana trophies.

Bonucci has also featured in two Champions League finals for the Italian giants.