According to Italian law, the 71-year-old has to leave to avoid a conflict of interests when he begins his third stint as Italian prime minister.

It is expected that Berlusconi will hand over the reins to current vice-president Adriano Galliani.

A brief letter from Berlusconi published on the official AC Milan website read: "The assumption of the role of Prime Minister forces me, in adherence to law 215/2004, to resign from the club responsibilities.

"With vivid regret, therefore, I resign with immediate effect from my role of president and of advisor to AC Milan."

Berlusconi stepped down once before as president of the Rossoneri, in 2004, but re-assumed his position in 2006 when he lost the general election to outgoing Italian prime minister Romano Prodi.