Moroccan authorities have arrested a Belgian national of local origin directly linked to the attackers who carried out the Paris shootings and bombings in November that killed 130 people.
The interior ministry gave only the suspect's initials in Arabic and said he fought in Syria with al-Nusra front before joining the so-called Islamic State group.
The suspect was arrested on 15 January in the city of Mohammedia, the statement added.
"He went to Syria with one of the suicide bombers of Saint Denis," it said.
Abdelhamid Abaaoud, a 28-year-old Belgian militant who authorities said was the ringleader of the Paris attacks, was killed with other suspects days after when police raided a house in the Saint Denis suburb.
Investigations showed that during his stay in Syria he built solid ties with IS leaders, including the ringleader of the Paris attacks.
The suspect was trained to handle different weapons and guerrilla tactics but left Syria through Turkey, Germany, Belgium then Netherlands from where he came to Morocco.
Morocco provided the tip-off that enabled French police to locate Abaaoud, has been holding Abaaoud's brother Yassine since October and has issued an arrest warrant for Salah Abdeslam, who is suspected of taking part in the attacks and is on the run.