Government sources said the request to question Rana, a key accomplice of Lashkar-e-Taiba operative David Headley, by Indian investigators has been sent to the authorities in the US after gathering evidence about his involvement in the planning of the 26/11 attacks.
"We are expecting a reply from the US by May-end on the request which was sent under the Mutual legal Assistance Treaty between the two countries," sources said.
Meanwhile, Home Secretary Gopal K Pillai said India's case against Rana has been strengthened after his claim before a Chicago court that he provided "material support" to the terrorists at the behest of the Pakistan government and its spy agency ISI.
"The case has been strengthened....what we have been saying, a belief that we already had. We are in the process of charge-sheeting Headley. In due course Rana would also follow," Pillai said on the sidelines of a function here.
Sources said after getting access to Rana, India may pursue with US authorities for his extradition as he has not entered into a plea bargain with the American authorities like Headley.
Rana in his defence, which is to be produced before the Chicago court, said his "alleged illegal acts of providing material support to terrorists -- were done at the behest of the Pakistani government and the ISI, not the Lashkar terrorist organisation".
49-year old Rana is accused of helping David Headley in setting up his office in Mumbai which the latter used as cover for his trips to the city for identifying targets.
India last year got access to Headley, who is currently in the US custody.