In its interim application, NGO Common Cause submitted that the alleged "blatant interference" by the Government is not only unlawful and a criminal offence, it amounts to contempt of court and the same has to be probed by a special investigative team (SIT).
It alleged that the CBI was not fit to probe the scam, as the agency at the instance of the government has "changed and diluted" a status report which it was to file before the apex court.
The NGO also submitted that the CBI officer who was supervising the investigation and who had filed its affidavit was replaced during the course of the probe.
It suggested that appointing a retired judge to head the SIT would help the court to monitor the case and add to the credibility of the probe by insulating it from political and corporate influences.
Earlier, advocate M L Sharma on whose petition the CBI probe was ordered into the alleged irregularities in the coal block allocation, mentioned before a bench headed by Justice R M Lodha the issue of reported interference of government in the probe.