While Karti was arrested in connection with the INX Media case in which the CBI has alleged that he was paid $1 million as bribe by the media company through foreign entities, Mr Chidambaram's role in granting FIPB approval to a offshore firm in the Aircel-Maxis deal is also under investigation by the agency.
Karti is fighting legal battles in the Supreme Court, the Madras High Court and the trial court, while Mr Chidambaram has knocked at the doors of the top court apprehending "continued harassment" to him and his family members through investigations being conducted by the CBI and Enforcement Directorate (ED) in these two cases.
His plea in the supreme court assumes significance as the CBI, in its charge sheet before a special court in the Aircel-Maxis case in 2014 against former telecom minister Dayanidhi Maran and others, had said it was probing how the then Finance Minister P Chidambaram had granted Foreign Investement Promotion Board (FIPB) approval to a deal involving a foreign firm when only the Cabinet Committee on Economic Affairs (CCEA) was empowered to do so.
However, the CBI and ED cases in the Aircel-Maxis deal could not withhold judicial scrutiny as the special court had in February last year discharged Dayanidhi Maran, his industrialist brother Kalanithi Maran and others saying the alleged charges were based on "misreading of official files", speculation and surmises of the complainant.
In April last year, the CBI had informed the Supreme Court that it was probing Mr Chidambaram's role in the alleged irregularities in grant of FIPB approval in Aircel-Maxis case.
During the hearing before the top court, BJP leader Subramanian Swamy, who has filed a petition in the top court in this regard, had said he had received a reply from CBI stating it was probing "all angles", including the FIPB clearance given to the deal by Chidambaram.
Mr Swamy had filed a private complaint in the 2G spectrum allocation case and the alleged scam in the Aircel-Maxis deal that had cropped up during the CBI probe.
On January 4 this year, the top court had directed the centre to file a status report on the probe being conducted in the Aircel-Maxis deal case.
The CBI had claimed that Global Communication Services Holdings Ltd had sought FIPB approval for 800 million USD for which only the CCEA was competent, but Chidambaram had given approval to the firm in March 2006.
"Further investigation is being carried out into the circumstances of said FIPB approval granted by the then Finance Minister. The related issues are also being investigated," the agency had said in its charge sheet.
Though the court has discharged Marans and others in the case, further probe by CBI regarding FIPB approval is still going on. Similarly, the ED is carrying out separate probe in the Aircel-Maxis deal.
An FIR, filed by the CBI on May 15 last year, had alleged irregularities in FIPB clearance to INX Media for receiving overseas funds to the tune of Rs 305 crore in 2007 when Mr Chidambaram was the Union finance minister.
While the CBI has alleged that Karti had received funds to the tune of Rs 10 lakh in the INX Media case, the ED has also registered a money laundering case in the matter.
Mr Chidambaram, in his petition before the supreme court, has said that his fundamental rights were being violated due to "illegal" investigations being carried out by the CBI and the ED and the central government has been "misusing" its probe agencies.
He has said that being the Finance Minister then, he had granted FIPB approvals in the INX Media case and the Aircel-Maxis case in the "normal course of official business"and in discharge of his functions, he has "never allowed any member of his family, including his son, or any other person to interfere with or influence the conduct of official business".