The Australian - The Moroccan government seized all issues of the country's leading French-language independent weekly because it contained a survey of how people viewed the king, officials and the magazine's publisher said.
"The Interior Ministry ordered the seizure of the issues of Telquel and Nichane following the printing of articles that violate the law," the ministry said.
The ministry gave no details about the content of the articles in Telquel ("As it is") and its Arabic-language sister publication Nichane which was also seized.
But Ahmed Benchemsi, Telquel's managing director, said it was because the magazine contained a poll about King Mohammed.
"The seized issue includes an opinion poll about the results of 10 years of the king's rule. Among other things, the poll showed that 91 per cent of Moroccans are very satisfied or satisfied with the king's performance.
"The authorities told us it is not acceptable in principle to do an opinion poll about the king. That is the reason for seizing Telquel and Nichane."
The reform-minded King Mohammed marked the 10th anniversary of his ascension to the throne on Thursday.
He is widely credited with turning Morocco into a more tolerant state after the 38-year rule of his late father, King Hassan, when dissidents were jailed, tortured or killed.
But the monarchy, religion, army and the issue of the contested Western Sahara region are still off-limits to an increasingly intrepid local media.
Journalists have been jailed or fined and newspapers shut down or seized in the past 10 years when reporters attempted to test the limits in those four areas.
Africa's last colony
Since 1975, three quarters of the Western Sahara territory has been illegally occupied by Morocco. The original population lives divided between those suffering human rights abuses under the Moroccan occupation and those living in exile in Algerian refugee camps. For more than 40 years, the Saharawi await the fulfilment of their legitimate right to self-determination.