New Delhi, April 24 -- Security outside the headquarters of the National Investigation Agency (NIA), where Mumbai attack accused Tahawwur Rana was kept in custody , was tightened on Thursday.

Rana will be questioned in detail by NIA in order to unravel the complete conspiracy behind the deadly 2008 attack.

Meanwhile, the Patiala House Court on Wednesday reserved its decision on a plea filed by the accused, seeking permission to speak with his family over the phone.

Rana's legal counsel, Piyush Sachdeva, argued that as a foreign national, he has the fundamental right to communicate with his family, who are anxious about his treatment while in custody.

The National Investigation Agency (NIA), however, opposed the request, citing the ong...