Monaco's Prince Rainier is in grave condition, and doctors cannot say whether the 81-year-old ruler will be able to survive the heart, lung and kidney problems that put him in intensive care.

Doctors said Friday his vital organs are failing, and it is uncertain if he will recover.

Prince Rainier, who was hospitalized more than two weeks ago with a chest infection, was connected to a respirator Tuesday after his condition suddenly worsened.

The prince assumed power in 1949 and is credited with transforming tiny Monaco into a modern and sophisticated destination for wealthy Europeans. Prince Rainier's movie star wife, American Grace Kelly, died in a car accident in 1982.