The CBI has questioned a former personal secretary of Dayanidhi Maran in connection with the spectrum allocation made during the tenure of the ex-telecom minister.

K Sanjay Murthy, an IAS of 1989 batch from Himachal Pradesh cadre, was quizzed yesterday on various policy decisions taken during Maran's tenure between 2004 and 2007, sources said.

Murthy, who is now Secretary (Administrative Reforms) with the Himachal Pradesh government, was also asked about allegations of former Aircel chief C Sivasankaran that his files gathered momentum only after he sold his controlling stake in the company to Singapore-based Maxis group, they said.

Sivasankaran had alleged in a statement before the agency that he was forced to sell his stake in Aircel by Maran and his brother Kalanidhi at a very cheap price to Maxis, which is considered closed to Dayanidhi and his brother Kalanithi.

The agency has registered a preliminary enquiry into sale of telecom spectrum during 2001-07 and is probing the allegations under it as Dayanidhi was telecom minister in the UPA-I government .