Italian former prime minister Silvio Berlusconi, who is currently in intensive care, is suffering from leukaemia and a lung infection, doctors said on Thursday.

The 86-year-old media mogul and senator, who has been in and out of hospital in recent years, was admitted on Wednesday to the intensive care cardiac unit at Milan's San Raffaele Hospital after suffering respiratory problems.

"Berlusconi is currently hospitalised in intensive care for treatment of a lung infection" and suffers from "chronic myelomonocytic leukaemia", a rare type of blood cancer, doctors said in a statement.

The magnate – a controversial, larger-than-life figure who elicits either admiration or disdain from Italians – has been dubbed "the immortal" for his longevity in politics.

He is currently a senator and leader of the right-wing Forza Italia party.

Chronic myelomonocytic leukaemia (CMML), which affects mainly older adults, starts in blood-forming cells of the bone marrow and goes on to invade the blood.

Berlusconi's cancer was in a "persistent chronic phase" and had not yet turned into "acute leukaemia", wrote doctors Alberto Zangrillo – the ex-premier's personal doctor – and Fabio Ciceri, the heads of San Raffaele's cardiac intensive care and haemotology units, respectively. (AFP)