"The Moroccan security services have just dismantled a terrorist structure as it was being formed," an official statement said, adding that the suspects would be charged on Monday.
The network was "composed of 17 elements linked to the radical Islamic movement having connections with small groups emerging at the Iraqi border and maintaining close ties with senior members of the Al-Qaeda organisation," it said.
One of the arrested was named as Mohamed Reha, a Belgian national of Moroccan origin, who was "known to have stayed in Syria and maintained close ties with North African Islamists in Europe."
Moroccan security services said they had been interested since March in the activities of Moroccan national Khaled Azig, a former theology student in Syria who made repeated trips between there and Turkey.
Azig returned to Morocco in June and was joined by Reha on September 29, in order to "recruit members for a terrorist cell," said the statement.
The arrests were made early this month in Rabat and Casablanca, Morocco's largest city, which was the target on May 16, 2003 of five suicide attacks that killed 33 people.
The security forces said the pair recruited extremists, including Brahim Benchekroun, 26, and Mohamed Mazouz, 32, two Moroccans who undertook military training in Afghanistan and were later detained at the United States detention centre at Guantanamo Bay, in Cuba.
"Khalid Azig and Mohamed Reha have in effect recruited individuals impregnated with extremist ideas," a police source said.
On November 15, Benchekroun and Mazouz, along with another former Guantanamo detainee, Redouane Chekkrouri, 33, were arrested on suspicion of helping an Al Qaeda member sneak into Morocco.
The arrests were followed by a security alert at airports, harbours, train stations, shopping centres and embassies throughout the country.
Ten days previously, a group calling itself the Islamic Tawhid Wal Jihad Group of Morocco, a name formerly used by Al Qaeda's Iraq frontman Abu Mussab al-Zarqawi, announced that it had declared war on the Moroccan state and King Mohammed VI.
Security officials dismissed the declaration as not credible.