Prince Albert of Monaco is engaged to marry South African former Olympic swimmer Charlene Wittstock, the royal palace said today.
The palace issued a statement announcing the engagement of "His Serene Highness", 52, and Miss Wittstock, 32, who worked as a school teacher before moving to the Mediterranean principality.
The palace did not indicate a planned wedding date, but the statement puts to rest months of speculation that the two long-time companions would tie the knot.
It will be the first marriage of a reigning prince since Hollywood actress Grace Kelly married Albert's father, Prince Rainier III, in 1956.
Princess Grace died in a car accident in 1982, casting a pall of tragedy over the family.
Laetitia Pierrat, a palace spokeswoman, said Albert met Miss Wittstock in 2000 when she was visiting Monaco for a swimming competition. She has lived in the principality since 2006.
Asked by The Associated Press whether Miss Wittstock might already be pregnant, Ms Pierrat said: "Honestly, I don't think so."
She added that she was not privy to such private matters, but if Miss Wittstock were, a formal announcement would probably have been made.
Ms Pierrat said that, according to protocol, royal couples must wait at least six months between the announcement of the engagement and the wedding day.
Royal watchers welcomed the announcement.
"It's been 30 years since Grace died, 30 years they've been waiting for a first lady, a princess, a dream beauty, glam. And voila!" said Colombe Pringle, executive editor of the French celebrity magazine Point de Vue, which covers Albert's private life regularly.
Ms Pringle told the AP that she had not heard any rumours that Miss Wittstock might already be pregnant, but she added, "Obviously, there is going to be an heir."
Albert took the throne in July 2005 after the death of his straight-laced father, who built the sleepy Mediterranean port into a tax haven for the rich and a glittering financial centre.
That same year, Albert acknowledged that he had fathered a boy, Alexandre, out of wedlock by a former flight attendant.
The following year, he acknowledged an American daughter, Jazmin Grace Grimaldi, now a teenager, born to a California woman. Neither can assume the throne because they were born out of wedlock.
While his father's reign was defined by his marriage to Princess Grace, Albert was known for being a long-time bachelor - so much so that in 2002 Parliament changed the constitution to allow one of his sisters' sons to take the throne if he never produced an heir.
Ms Pringle suggested that Albert's advancing age, and the long time since his mother's passing, meant that the time was right for him to give up bachelorhood.
"He's 50-something. It's time," she said.
She said Miss Wittlock had spent their years together preparing for this.
"She has learned a lot, she has done a good personal job to fit with her job, there are many years of learning there behind her.
"Now it's a question of involvement and engagement in her new role. We'll see how she does.
"She really wanted the job."