The apex court termed as "highly improper" the conduct of Kumar whose NGO filed a joint petition with others against Maran and subsequently writing a letter to the CBI and publishing an article in a magazine giving a clean chit to Maran.
"We can clarify that this letter should not in any way affect the investigation and if you (CBI) think that this man has done something wrong you can proceed against him in accordance with law," a bench comprising justices G S Singhvi and K S Radhakrishnan said.
The bench said "writing a letter to the CBI after filing the petition was highly improper and this letter deserves to be thrown in the dustbin."
The bench made it clear that "backing out" of one of the petitioner or his coming out in support of former minister should not affect the investigation.
"How does the change of stand affect the CBI investigation," the bench told the CBI and referred to the submission of advocate Prashant Bhushan that the agency was not taking any action against Maran, who has been accused by the agency of "coercing" a Chennai-based promoter to sell his stakes in Aircel to Malaysian firm Axis in 2006.
"You (CBI) have to take action in accordance with law and there is no question of permission or order. If facts are correct you must have completed the investigation," it said.
Bhushan, who was appearing for the NGO, Centre for Public interest litigation (CPIL), accused the CBI of going slow by saying that though the FIR against Maran was lodged in October last year the investigation has not been completed. (MORE)