Department of Telecommunications (DoT) has handed over 15 files sought by the CBI in connection with its probe into increase of spectrum bandwidth for Airtel and Vodafone between 2001 and 2003 during when NDA was in power.

The agency, which is likely to file a charge sheet in the case in the first week of October, had sought certified copies of the files pertaining to increase of spectrum beyond 4.4 MHz upto 6.2 MHz, beyond 6.2 MHz up to 8 MHz, and beyond 8MHz up to 10 MHz to these companies when late Pramod Mahajan was the telecom minister, official sources said here on Monday.

The CBI had registered a case against the then Telecom Secretary Shyamal Ghosh and Deputy Director General (Value Added Services) J R Gupta and unknown officials of Bharti Cellular (now known as Bharti Airtel), and Hutchinson Max and Sterling Cellular (now known as Vodafone Essar) last November.

Both Bharti Airtel and Vodafone have, however, denied the allegation levelled against them saying they had always maintained the highest standards of corporate governance and regulatory compliance.

A letter from Assistant Wireless Advisor M K Patnaik to CBI’s Deputy Superintendent of Police R A Yadav listed all the 15 files pertaining to the decision of increasing the spectrum bandwidth of the two telecom operators, the sources said.

CBI has sought certified copies of licenses, amendments issued by wireless planning and coordination wing of the ministry and subsequent additional spectrum issued to them.

They said documents related to additional spectrum allocation to three companies — beyond 4.4 MHz upto 6.2 MHz, beyond 6.2 MHz up to 8 MHz, and beyond 8MHz up to 10 MHz — should be provided to the agency “urgently”.