Beretta took over from the sacked Andrea Mandorlini in November when the club were languishing close to the relegation zone and presided over a marked period of improvement for the club, who finished in 13th place.

Siena posted wins over Roma, Fiorentina and Juventus and held champions Internazionale to a 2-2 draw during Beretta's six months at the helm, which culminated in the Tuscan club beating their Serie A record of 43 points in a single season.

"The bitterness has passed," said Beretta, whose previous spell at Siena came to an end when he stood down at the end of the 2006/07 campaign.

"I thank all the fans who have supported me as it gives me great pleasure to know that I have left a good memory.

"This is not my choice, but one made by the club and they are free to make the decisions they want to.

"For the time being I have no offers but sooner or later something will arrive."

Former Cagliari and Ascoli boss Marco Giampaolo is the early favourite to replace Beretta.