Doctors say the health of Monaco's Prince Rainier continues to deteriorate and they describe his condition as extremely guarded.

A palace spokesman Saturday said the 81-year-old monarch's health has worsened in the last 24 hours - with his heart, lungs and kidneys failing.

One of Europe's longest reigning monarchs, the prince was hospitalized more than two weeks ago with a chest infection. He was connected to a respirator Tuesday after his condition suddenly worsened.

The prince succeeded his grandfather as head of Monaco's constitutional monarchy in 1949. He is credited with transforming the small Mediterranean principality into a sophisticated destination for wealthy Europeans.

His American movie star wife, Grace Kelly, died in a car accident in 1982. His only son, the bachelor Prince Albert, is heir to the throne.