Siddiqui was produced before a court which remanded him to police custody till August 14.
He was earlier arrested on July 29 by the Anti-Terrorist Squad under Unlawful Activities Prevention Act from suburban Mira Road.
The ATS also had seized a lot of pamphlets of the banned SIMI from him and was its custody. He was arrested again for his alleged involvement in the July 11 bomb blasts, ATS sources said.
