Detained yesterday in a Bamako suburb, the man is believed to have taken part in attacks in March, August and November that left more than 30 people dead , including a deadly assault on the upmarket Radisson Blu hotel he allegedly masterminded.
"He was planning to stage an attack on western targets this weekend in Bamako," said a source to AFP.
The suspected is believed to attacked a bar and restaurant in Bamako in March 2015 in which five people died, including two foreigners, the sources said.
A security source close to the investigation said the Mauritanian had also been involved in a failed attack in March 21 this year on the Azalai Nord-Sud hotel in Bamako, where the EU mission is based.
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Code-named "Ibrahim number 10", the suspect was "the shooter at La Terrasse", and he planned the Radisson Blu, Sevare and Nord-Sud attacks, the source said.
"He quickly confessed after his arrest yesterday (Thursday) at around 8:00 pm (2000 GMT)," the source added.
Another security source said weapons and grenades were found at the suspect's home in Bamako.
The March 7, 2015 grenade and gun attack on La Terrasse bar left five people dead -- three Malians, a Belgian and a Frenchman. It was claimed by an affiliate of Al-Qaeda in the Islamic Maghreb (AQIM), the jihadist group's North African branch.
The November 20 attack on the Radisson Blu left 20 people dead, including 14 foreigners. AQIM also claimed responsibility for the assault.