One ex-telecoms minister is already in custody and a police spokeswoman said cases of corruption and conspiracy were registered against his predecessor, Dayanidhi Maran, and Maran's elder brother, the media baron Kalanithi Maran.

Police raids of premises belonging to the Marans were "conducted at Delhi and Chennai", Central Bureau of Investigation (CBI) spokeswoman Dharini Mishra said in New Delhi.

The CBI also registered cases against Malaysian tycoon Ananda Krishnan, owner of the Malaysia-based Maxis group, among others.

Under Indian law, the registering of cases, known as a First Information Report (FIR), means that police will now investigate to see whether there is enough evidence to lay formal charges.

The CBI announcement is a fresh headache for Premier Manmohan Singh's government, which has been badly shaken by the alleged telecom licensing scam in 2008 that the national auditor said may have cost the country up to $39 billion in lost revenue.

In April, police charged Maran's successor, A. Raja, with abuse of power and conspiracy over accusations he rigged rules for the sale of second-generation (2G) mobile licences in 2008 to favour some firms.

Dayanidhi Maran quit as textiles minister in July after accusations that Maran's family-owned Sun TV Network also got kickbacks in return for favours in granting mobile licences.

Former Aircel mobile company chief C. Sivasankaran alleged that Dayanidhi Maran denied his company mobile licences and forced him to sell out his holdings to the Maxis group in 2006.

All the accused have denied wrongdoing.

More than a dozen people including Raja, top government officials and business executives are already in custody over the alleged widespread fraud.

Maran and Raja belong to the Dravida Munnetra Kazhagam party, a key member of the Congress-led government coalition.

Copyright AFP (Agence France-Presse), 2011