The sources said the Supreme Court would be intitimated about the agency's finding during next hearing, scheduled next month.
They said a final decision whether to close the enquiries or further probe them will depend on the directions of the Supreme Court which had handed to it over the investigation.
They said a journalist from a TV channel and a senior executive of a leading newspaper group have already been examined by the agency.
Besides, executives of Reliance, Unitech and Tata Motors have also been examined by the agency in connection with its enquiries.
The apex court bench, headed by Justice G S Singhvi, had ordered CBI to probe 14 issues that were identified by the investigating agency after going through the transcript of the Radia tapes submitted to it by the Income Tax department.
The court has also referred one of the matters to the Chief Vigilance Officer of the Department of Mines for investigation and another to the Chief Justice of India.
"Radia's conversations reveal deep-rooted malice by private enterprises in connivance with government officials for extraneous purposes," the Supreme Court had said.
Using strong words, the court had said the telephonic conversations suggest corrupt means being adopted by private parties to extract gains.