The 26-year-old midfielder will undergo a medical in Glasgow next week, having flown into the city earlier in the week to thrash out the move to Parkhead.

Donati will be Celtic manager Gordon Strachan's fourth summer signing, as the Glasgow giants aim for their third successive title.

Scott Brown joined from Hibernian, while Motherwell and Hibs strikers Scott McDonald and Chris Killen were snapped up on free agency deals.

Donati began his career at Atalanta before he transferred to AC Milan in 2001. In recent seasons he has had loan spells at a number of Serie A clubs, including Parma, Torino and Sampdoria, and last season was a regular for Atalanta.

"We are delighted that Massimo has signed for the club," a Celtic spokesman said. "He is a player of real quality and we're sure he will be a great addition to our squad."