During the enquiry which started about 15 days back, the CBI has sought and collected documents from the Delhi-based All India Football Federation on several Indian football clubs, they said.
Under the scanner, is the role of an alleged match fixer based in Singapore in rigging the results of matches, they said.
The officials refused to give any details about the suspects named in the preliminary enquiry and details of allegations as it could hamper the probe which is at a nascent stage.
They said the agency has received some documents while some are still awaited.
The agency has also sought cooperation of several Indian football clubs in joining the investigation, they said.
The CBI cannot conduct searches, arrests or question through summons under the preliminary enquiry, they said citing the law.
The central probe agency depends on cooperation of stakeholders during the preliminary enquiry and registers an FIR when it has prima facie material indicating a crime, they said.