Separatist agitator Sunday Adeyemo, and his wife, Ropo are being interrogated by Beninese security operatives.
According to Beninese website, RFI, the political enforcer and Ropo have been undergoing questioning since Wednesday.
Adeyemo, known to the public as Sunday Igboho was meant to be arraigned in court on Thursday but he is yet to show up.
His supporters had earlier converged at the court but later moved to the Brigade Criminelle where he is being held.
Igboho was arrested at Cardinal Bernardin International Airport, Cotonou, with his wife on their way to Germany on Monday night.
He was declared wanted by the Department of State Services (DSS) earlier in July after a raid on his Ibadan house.
Two people were killed by the DSS in the late night raid while 12 other persons were arrested and later paraded in Abuja. They have since been charged to court.
It is not clear why the proceedings have not commenced, but sources say the elongated interrogation may not be unconnected with how he got Benin passport said to be fake.
It is understood that Igboho had filed for political asylum in Germany before his arrest.