Prince Rainier, ruler of Monaco, was declared by his doctors on Friday in a critical condition due to the weakness of his cardiac, respiratory and kidney functions, palace officials said in a statement.

According to reports reaching here, an artificial respirator was applied on the 81-year-old sovereign to keep him alive.

Rainier III, Europe's longest-reigning monarch, was rushed into intensive care on Tuesday when his health took a dramatic turn for the worse.

Also on Friday, French President Jacques Chirac called Prince Albert, 47, successor to Rainier as ruler, to inquire about Prince Rainier's condition, and expressed his concern and friendship for him, his family, and the people of Monaco.

Rainier ascended to power in the tiny Mediterranean territory in 1949.

He is the second longest-reigning monarch in the world after Thailand's King Bhumibol Adulyadej.

After a heart surgery in 1994, his health conditions have worsened.

Source: Xinhua