It added that justice would be served.
DSS Spokesman, Dr Peter Afunaya, said this during a brief chat with our correspondent on Friday.
Afunaya said, “Army brought him to us. Justice will take its course.”
He, however, refused to answer further questions.
Agu was arrested around Upper Iweke in Onitsha, Anambra State, on Thursday for wearing a Biafra outfit.
The state has witnessed several incidents of violence in the last couple of weeks ahead of the governorship election next month.
Authorities believe separatist groups, notably the Indigenous People of Biafra, are behind the attacks but IPOB denies this.
Agu has been an ardent supporter of the Biafran struggle and had accused the Nigerian government of marginalising Igbo people .