During an in-chamber hearing, district judge I S Mehta allowed the National Investigation Agency's plea seeking custodial interrogation of Rehman on the ground that it has to unearth the entire conspiracy which led to the bombings that claimed 16 lives, court sources said.
They said the NIA told the court that Rehman was a key IM operative and he may give some vital information against the banned group's members who were involved in the blasts.
During the hearing, the court also sent suspected IM operatives -- Syed Maqbool, Imran Khan and Mohammad Aftab Alam -- to judicial custody till March 23.
The NIA had earlier interrogated Maqbool and Imran and had taken them to Hyderabad in connection with the probe. It told the court that Maqbool and Imran have revealed some important facts about the blasts, the sources said.
The court had also issued non-bailable warrants against IM founder Riyaz Bhatkal and nine other operatives of the banned group in connection with the Hyderabad blasts -- Iqbal Bhatkal, Mohsim Chaudhary, Amir Reza Khan, Dr Shahnawaz Alam, Asadullah Akhtar, Ariz Khan, Mohd Khalid, Mirza Shadaab Beg and Mohd Sajid.
According to the sources, the NIA had told the judge that the conspiracy behind the Hyderabad blasts was hatched by the IM modules. The NIA said the blasts took place in Hyderabad on the alleged instructions of Riyaz Bhatkal.