CBI sources said the agency might register the cases this week against companies which have got blocks in Chhattisgarh, Jharkhand and Karnataka.
They said preliminary enquiry has indicated alleged irregularities on part of the beneficiary companies in utilisation of blocks.
The agency, which has registered a preliminary enquiry after Central Vigilance Commission referred to it the case of alleged irregularities in coal block allocation and utilisation, is likely to register more than one case.
The agency has already questioned senior bureaucrats who were overseeing the allocation of coal blocks during 2006-09, CBI sources said.
Meanwhile, the agency is also taking into cognisance the Comptroller and Auditor General report on coal block allocation which was tabled in Parliament on Friday.
The sources, however, made it clear that CBI would not be going into policy issues but will limit its role to aspects where criminality could be established.
The agency has also questioned members of the screening committee including Secretaries and Joint Secretary in the Ministry, CBI sources said.
They said the questioning of the Coal Secretaries, who also chair the screening committee, was done to understand the issues involved in the allocation of coal blocks during the period and so far agency has not found any irregularity on their part.
The agency has shortlisted nearly 15 companies which allegedly violated norms of allotment of coal blocks and questioning of their officials is going on, they said.