In a new twist to the alleged irregular allotment of 2G spectrum, the CBI has informed the Supreme Court that it was investigating the allegation that Unitech got spectrum in 2008 during A Raja's tenure as Telecom Minister by hiding the fact that it was a front for the Tata group.

Citing the report of the Serious Fraud Investigation Office , SFIO into telephone intercepts of former corporate lobbyist Niira Radia, advocate Prashant Bhushan, appearing for NGO 'Centre for Public Interest Litigation, told the court that Unitech was used as a front by the Tata group as Swan was used by Reliance Telecom.

When a bench of Justices H L Dattu, P C Ghose and S A Bobde asked the CBI for a report on this issue, special counsel for the agency K K Venugopal said the matter was already under investigation and that the agency had registered a preliminary enquiry.

Venugopal said the tapes in question were sent for forensic examination and were found to be genuine. He told the court that steps are being taken to examine the concerned persons. The investigations will be over soon.