The AU's Peace and Security Council (AUPSC) said in a statement that the suspension was in line with AU protocols and would remain in place until constitutional order was restored in Gabon.
The coup came after allegations of electoral misconduct in the country's recent elections, in which President Ali Bongo secured a third term.
In the early hours of Wednesday, military officials declared their assumption of power via national broadcast. They nullified the election results and detained Bongo and other government officials.
The AUPSC condemned the coup and called for the immediate release of Bongo and other detainees. It also urged the military to respect the constitution and to return power to civilians.
Gabon is the latest African country to experience a military coup in recent months. In late July, Niger's military seized power after the country's president, Mohamed Bazoum, was declared the winner of a disputed election.
The AU has condemned both coups and called for the restoration of constitutional order in both countries.
The suspension of Gabon's membership is a significant blow to the country. The AU is a major political and economic bloc in Africa, and Gabon's membership is important for its access to AU funding and resources.
The coup also raises concerns about the stability of Gabon, which is a major oil producer. The country is already facing economic challenges, and the coup could further destabilize the situation.
It remains to be seen how the AU will respond to the coup in Gabon. The AU has a history of suspending the membership of countries that experience military coups, but it has also been criticized for not doing enough to prevent them.
The coup in Gabon is a reminder of the fragility of democracy in Africa. It is also a reminder of the importance of the AU in promoting peace and stability on the continent. (ILKHA)