The Central Bureau of Investigation has named Castron Technologies Ltd., BLA Industries Pvt. Ltd, the managing director of BLA Industries and some public and private officials in the first information reports (FIRs).
The formal complaints will be followed up with investigations and court cases later.
The probe is being conducted into the coal blocks allocations during the period of 1993 to 2005.
Searches were also being conducted in Jharkhand's Dhanbad, Kolkata, Mumbai and Madhya Pradesh's Narsimpur, officials said.