The head of the Central Bureau of Investigation, or CBI, has told the Joint Parliamentary Committee (JPC) that it is investigating two transactions related to the Tata Group, the ownership of Loop Telecom , and the controversial Aircel-Maxis deal.

CBI Director AP Singh , who made a 45-page presentation to the JPC, said the agency had failed to unearth anything incriminating against Niira Radia, corporate lobbyist and head of a corporate communication firm, whose leaked conversations with assorted bigwigs have riveted the nation.

The two transactions involving the Tatas are an advance of Rs 1,700 crore given by Tata Group company Tata Realty and Infrastructure Ltd (TRIL) to Delhi-based realty major Unitech, and a real estate transaction in Chennai involving another group company, Voltas .

The Tatas and Unitech have vehemently denied there was anything untoward in the entire transaction.

Singh, who was accompanied by a number of officials, said the agency was also awaiting response from the attorney-general of Mauritius to queries seeking information about the source of funding and ownership of Loop Telecom, which is alleged to be linked to the Essar Group , and Delphi Investments. The latter is the entity to which Reliance Telecom-part of the Anil Ambani group-had sold its stake in Swan Telecom, alleged to be a major beneficiary of the so-called 2G scam.

The response from the Mauritius authorities could form the basis of a chargesheet the CBI could file in early July.

The deposition of the CBI director was described to ET by people familiar with it. They declined to be identified because the JPC''s proceedings are confidential.

In the case of Loop, the CBI is probing whether it was a front for the Ruias of Essar. It is widely believed that Loop and Essar would be named in the third chargesheet. Both Loop and Essar have strongly denied these allegations.

The agency has so far filed two chargesheets. It has arrested former telecom minister A Raja, and the owners of Swan Telecom (now known as Etisalat DB) and Unitech Wireless . These businessmen have been accused of conspiring with Raja to grab airwaves and licences at below market prices in early 2008. The CBI, under the instruction of the Supreme Court, is also investigating the period between 2001 and 2007.

Kanimozhi, daughter of DMK leader M Karunanidhi , has also been jailed because of a Rs 200-crore payment by DB Realty , the promoter of Swan Telecom, to a television channel in which she is a shareholder. In consonance with the understanding reached among the members before the meeting, the CBI director was asked only a few questions, mostly on minor issues. It was decided that he would be allowed to make his presentation on Tuesday, leaving his crossexamination for some other day.