Top industrialist Ratan Tata and corporate lobbyist Niira Radia were today quizzed by Parliament's Public Accounts Committee (PAC) in connection with alleged irregularities in the 2G spectrum allocation.

Radia, whose tapped phone conversations with politicians, corporates, bureaucrats, and journalists form a key part of the investigations into the 2G spectrum scam, is believed to have told the Committee that some of the tapes of her purported talks were doctored.

"She told us that some tapes are genuine while some are doctored," a member of the PAC said.

He said she was also asked about the letter Tata had reportedly written to Tamil Nadu Chief Minister M Karunanidhi praising the then Telecom Minister A Raja.

Radia, chairperson of Vaishnavi Corporate Communications, appeared before the PAC alongwith two senior colleagues Manoj Warrier and Yateesh Wahaal.

Another PAC member said that Radia was evasive while answering to several questions. "'I dont know. I cannot remember' was her refrain to many questions," said the member.

The PAC quizzed Radia for nearly two hours. She had reached Parliament just before 11:00 a.m., the time alloted for recording of evidence. However, the members had a long discussion among themselves for over an hour and she was finally called in just past noon.

Tata, Chairman of Tata Sons, appeared before the Committee after 3:00 p.m. He is understood to have been asked the reasons for Tata Teleservices' interest in launching GSM mobile services when it was already a key player in the CDMA technology for such services.

One of the questions put to him was regarding the Group's dealing with journalists and whether it was a practice to make payments to them for publishing favourable news reports.

The panel, headed by senior BJP leader Murli Manohar Joshi, is understood to have sought clarifications from Radia on the tapped conversations which include allegations of trying to influence portfolio allocation to ministers in the UPA-II government.

In the calls, Radia is allegedly heard making efforts to ensure that Raja gets the Telecom portfolio. Raja is now in jail in connection with the 2G scam.

The PAC 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 tomorrow.