Monaco 's Prince Rainier was in a "worrying" condition today and remains attached to an artificial respirator three days after he was taken into intensive care.
The 81-year-old prince, who was married to the late film icon Grace Kelly, has been suffering from a lung infection complicated by cardiac and kidney problems.
"The state of health of His Most Serene Highness Prince Rainier III, who is still in intensive care under artificial respiration in Monaco 's Cardiothoracic Centre, remains worrying," the palace said in a medical bulletin.
A specialist from Paris was consulted late on Thursday given "the gravity of the situation" and decided to keep the prince in intensive care, the palace said.
The prince, one of the world's longest serving monarchs, rules the tiny state of Monaco on the French Riviera.
He had initially been responding well to treatment following his admission to the cardiothoracic centre on March 7.
Rainier, whose Grimaldi family has ruled the low-tax haven for seven centuries, has been in and out of hospital in recent years with both lung and coronary problems.
Born on May 31, 1923, Rainier has cut a lonely figure in recent years as media attention has shifted from him to the turbulent lives of his three children.
Princess Grace, the Hollywood actress he married in 1956, was killed in a car crash in 1982.