Former chief of CBI Ranjit Sinha had "inappropriate meetings" with those being investigated by his agency, abused the powers of his office and must be investigated, the Supreme Court ruled on Thursday.

A bench headed by Madan B Lokur said that Sinha was guilty of trying to subvert the inquiry against telecom firms and coal companies’ executives who were charged with colluding with government officials to get out-of-turn mobile network licenses and free spectrum or airwaves.

The evidence furnished against Sinha was pivoted largely on a visitors diary at his home. The entries showed house calls were made regularly by those being investigated in the telecom case, and the coal scam, which rests on blatant irregularities in the distribution of mining licenses by earlier governments to private firms.

The allegations against Sinha were filed by lawyer-activist Prashant Bhushan and Common Cause, an NGO based in Delhi. "The court has held that it was inappropriate for the CBI chief to meet the  accused in the absence of the investigating officers," Bhushan said on Thursday.

The court has said that Sinha's meetings with those accused in the telecom and coal scams should be examined by the Central Vigilance Commission, the agency that deals with governmental corruption.

The court asked the CVC to file response by July 6.

The SC bench also dismissed Ranjit Sinha's plea seeking prosecution of lawyer Prashant Bhushan for alleged perjury.

The bench had reserved its judgment on April 13 in the matter in which Sinha had claimed that a "hidden hand" was the "controlling mind" of Bhushan and had accused him of interfering and scuttling the probe into the coalgate.

The NGO, in its application, had submitted that since the Anti-Corruption Bureau (ACB) of Delhi Police had not lodged an FIR on its November 25, 2014 complaint, there was a need for a court-monitored probe for alleged abuse of authority by Sinha as the then director of CBI.

However, Sinha had rejected the NGO's claim that he and a few other senior officers of the level of joint director repeatedly overruled the investigating officers (IOs) and forced them not to register FIRs/RCs in cases where preliminary enquiries had been registered and directed closure of the cases.

In the plea for perjury against the NGO and Bhushan, Sinha's counsel had said "there is not a single case in which Sinha overruled the unanimous opinion of the officers working under him with regard to recommending closure in which they have recommended conversion to a regular case.