India, April 13 -- The National Investigation Agency (NIA) is questioning 26/11 Mumbai attacks conspirator Tahawwur Hussain Rana based on various leads gathered by the probe agency during the course of its investigation, including a large number of phone calls between him and his co-conspirator David Coleman Headley alias Daood Gilani, a US citizen currently in prisons in that country.

The 64-year-old Pakistani-origin Canadian businessman was brought to the NIA headquarters early Friday morning after a Delhi court granted 18-day custody to the central probe agency, following his extradition from the United States.

Tahawwur Hussain Rana is being questioned on his suspected links with the officials of Pakistan spy agency Inter-Services In...