Italy's most wanted Mafia boss, Matteo Messina Denaro, who was captured in January after being on the run for 30 years, is in an irreversible coma, ANSA news agency reports.
Messina Denaro is suffering from colon cancer and his doctors say he will not recover.
At his own request, life-sustaining measures have been discontinued, doctors from the hospital in the central Italian city of L'Aguila said.
In early August, the 61-year-old Mafioso underwent intestinal surgery at San Salvatore Hospital in the central Italian city of L'Aquila.
While the operation was successful, his advanced colon cancer caused an irreversible deterioration in health, ANSA cited sources as saying.
On Friday, Messina Denaro suffered significant bleeding and shortly after went into an irreversible coma, ANSA reported.
Messina Denaro, the convicted head of the Sicilian Cosa Nostra Mafia, was captured by police in January after three decades on the run.
The Mafia boss, who had long been considered Italy's most-wanted fugitive, was captured by a specialised police unit at a cancer clinic in Palermo where he was undergoing treatment under a false name.
He was sentenced in absentia to life in prison for his role in a series of grisly murders and car bombings in Italy.
Among other crimes, he is blamed for the 1992 car bombings that killed leading anti-Mafia prosecutors Giovanni Falcone and Paolo Borsellino, among others.
Messina Denaro was considered a close confidante of former Mafia crime bosses Bernardo Provenzano and Salvatore "Toto" Riina.
Australian Associated Press