BRUSSELS (AP) — This time, Belgium’s royal family came out swinging.

Crown Prince Philippe, 52, had been depicted in a book as less of a man than is needed to become the next king of Belgium. Again.

So, in an exceptional move, the royal palace struck back this week with an official complaint to a media ethics body against a journalist who published "Royal Questions," a new book that includes damaging allegations about the crown prince’s character and marriage.

The royal household almost never deigns to answer allegations but the crown prince himself also made an equally rare public denial to the book’s allegations last week.

"The day that Mathilde said ‘Yes’ to my proposal was the happiest day of my life," he said.

‘’It is extremely rare to have a reaction like that," historian Marc Reynebeau said Friday in a telephone interview. ‘’It is as if they wanted to show: ‘You can claim whatever, but don’t exaggerate."’

The image and credibility of the royal family matters in this European Union nation, which is riven by divisions between its 6.5 million Dutch-speakers and its 4.5 million French-speakers. Three things still unite Belgium: Admiration for the king, a taste for fries and beer and a love of the national soccer team.

Journalists on Friday also questioned the significance of author Frederic Deborsu’s probing into the life of Philippe, who is expected to take over from King Albert.

Allegations about " his ‘forced marriage,’ the birth of his children in a hospital specializing in artificial procreation," the journalist group AJP said, "are they really in the public interest?"

For most of his life, the crown prince has been seen as a less-than-credible successor for his father, who is now 78.

Philippe was considered aloof and awkward, with the charisma of a civil servant. Until his engagement a dozen years ago, he was seemingly headed for terminal bachelorship.

‘’The general perception is that he is not up to the job to become king," Reynebeau said. ‘’Nobody knows, of course, because it is all speculation."

King Albert, who succeeded his brother in 1993, saw his own image darkened a dozen years ago when he had to acknowledge that he had fathered a daughter out of wedlock.

The scandal caused by Deborsu’s book comes on the heels of a major municipal election victory by the separatist N-VA party in northern Flanders last month. The party aims to break up the bilingual nation along linguistic lines and is already looking forward to nationwide elections in 2014.

If the country breaks up, Belgium’s royal house would become obsolete.