CBI sources said for its probe the agency needed some crucial files related to coal block allocation process from the ministries of Coal, Cement, Power and Department of Industrial Policy and Promotion.
While the sources maintained that a few files have been received, some of the crucial files are still not handed over to them citing staff constraint and other such excuses.
The sources made it clear that though their work might have hampered a bit because of delay in getting papers it will not affect the overall probe which the agency wants to complete in two months.
They also conceded that since the number of documents which are needed for the probe are huge in number and stored in over 70 trunks in a Coal Ministry godown, it may be difficult to trace them.
The agency is also planning to examine members of screening committee which was part of the coal blocks allocation process.
CBI sources said examination could be to take their help in understanding the alleged irregularities in the coal block allocation and their utilisation by the allottees. They, however, clarified that examination process would begin only after completion of scrutiny of records.
The CBI had initiated a preliminary inquiry in connection with the alleged irregularities in the utilisation and allocation of coal blocks allocated to private companies between 2006 and 2009 after CVC referred the case to it.