Moroccan authorities have rounded up thousands of purported terror suspects in recent years and while they "regularly discover terrorist cells ... nothing led us to foresee an act of this magnitude," Mr. Naciri said.
"Morocco has an international image of welcome, hospitality and tourism," he said "An act of this magnitude will leave its mark."
The government announced in January that it had arrested 27 suspected terrorists with links to AQIM in the southern region of the country. But a video appeared on YouTube last week featuring men claiming to be Moroccan members of AQIM and threatening to "attack Moroccan interests," the Guardian reported.
The Casablanca attack in 2003 was the work of a local Islamic militant group and did not have ties to Al Qaeda, according to an analyst quoted by Reuters.
"Would-be attackers in Morocco are usually youths from deprived urban areas who have low terrorist capabilities and no connections with established groups," said Anna Murison of Exclusive Analysis.
But several analysts said they suspected AQIM involvement in the latest bombing. U.S.-based corporate intelligence firm Stratfor said an attack on a soft target popular with tourists, as in the Marrakesh blast, "fits AQIM's target set."