The Public Accounts Committee (PAC ) probing the alleged irregularities in the 2G scam has asked Reliance Communications Chairman Anil Ambani, Etisalat DB Telecom CEO Atul Jhamb, S-Tel CEO Shamik Das and Unitech Wireless Managing Director Sigve Brekke to appear before it today. Top industrialist Ratan Tata and corporate lobbyist Niira Radia were quizzed by PAC on the issue on Monday. The (PAC) Chairman Dr. Murli Manohar Joshi said that there is no conflict between PAC and JPC probing the alleged irregularities in the 2G scam. Speaking to reporters after questioning top industrialist Ratan Tata and corporate lobbyist Niira Radia in New Delhi, Dr. Joshi said that both the committees have their areas of work. He said, while JPC has been given terms of reference, the PAC is working as per the rules and mandate given to it. Dismissing reports of conflict between the two, he said that various agencies and committees are also probing the scam. Regarding questioning, he said that corporate lobbyist Nira Radia was evasive while responding to the queries but Tata Chairman Rattan Tata was candid and clear. Last week, CBI has filed its first chargesheet in the case against Former Telecom Minister A Raja and eight others. Raja is in jail for alleged irregularities in the allocation of 2G spectrum licenses. A Joint Parliamentary Committee (JPC), chaired by Congress leader P C Chacko, has also been set up to look into all the details of the 2G spectrum allocation from 1998 to 2008.