New Delhi, Dec. 26 -- A special court on Friday extended the custody of two key accused being investigated by the National Investigation Agency in connection with the deadly Red Fort blast case, even as the anti-terror agency continues to unravel the larger conspiracy behind the attack.

Additional Sessions Judge Prashant Sharma granted the NIA ten more days of custody of accused Yasir Ahmed Dar while allowing the agency to interrogate Dr Bilal Naseer Malla for a further eight days.

The court accepted the prosecution's submission that sustained custodial interrogation was necessary to trace the remaining links of the terror network and verify the material collected so far.

According to the NIA, the car bomb blast outside the Red Fort on...