The French magazine Point de Vue reported the 50-year-old reputed former playboy intends to marry Wittstock, 30, in Monaco later this year.
"While the date is not yet fixed, two sources confirm that preparations are under way for a royal wedding at the end of the summer," the Daily Telegraph quoted the French magazine as saying.
The Mediterranean principality has not celebrated the wedding of a ruling prince since 1956, when Prince Rainier, Albert's father, married Hollywood icon Grace Kelly, the Telegraph noted.
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