STF was formed only recently by the Madhya Pradesh High Court after Singh filed a petition, demanding a CBI probe into the alleged rigging of the entrance examinations for professional courses.
However, the senior Congress leader said the probe by the state officers could not be independent.
"STF probe into the MPPEB scam is totally slack and is aimed at protecting the Chief Minister, his family, influential politicians and officials close to him," Singh said after meeting Justice Chandresh Bhushan here, who heads the SIT which is monitoring the probe.
"The way the probe is going on, the accused will not get punished and therefore I have demanded a CBI probe. How can an official, whose confidential report will be written by the Chief Minister, will be able to probe a case against him?" Singh asked.
He also alleged that the computer hard disks seized from the possession of MPPEB officials were tampered with to protect some influential people.
The former Chief Minister also said he was going to set up a toll-free number at his residence so that people can give information about the MPPEB scam, the MP Public Service Commission scam and the mining scam.
Identity of the caller will remain confidential, he said.

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