Adding to former Union finance minister P. Chidambaram’s woes, the Union law ministry on Sunday formally allowed the Central Bureau of Investigation (CBI) to prosecute the senior Congress leader in the INX Media case.With investigation already underway in the case, the probe agency, which had already arrested Chidambaram’s son Karti in the matter, is now likely to take steps to arrest the former Union minister.When contacted, P. Chidambaram declined to comment on the matter.A senior official familiar with the development, said that former Reserve Bank of India governor D. Subbarao was also likely to join the investigation. The CBI, however, did not offer any comment on the matter. Subbarao had served as the finance secretary before he became the RBI governor in 2008. “The CBI is likely to ask him to join the investigation as well, since he was also at the helm of affairs at the time,” the person said, seeking anonymity.In April 2018, the Enforcement Directorate had also asked Subbarao to join the probe in the case to investigate the investment proposal by INX Media directors Peter and Indrani Mukerjea. It had been approved by officials of the then Union finance ministry, when Subbarao was the finance secretary.CBI had registered an FIR in May 2017 for alleged irregularities in the Foreign Investment Promotion Board (FIPB) clearance to INX Media for receiving overseas funds to the tune of ₹305 crore in 2007, when Chidambaram was the finance minister in the United Progressive Alliance (UPA)-1 government.Chidambaram has already been summoned and quizzed by the agency because of his alleged role in connection with the FIPB clearance, while Karti Chidambaram has been charged in the case.CBI had sought the law ministry’s opinion on taking action against Chidambaram. It has now got the assent to prosecute him.The CBI and the ED on 25 January had told the Delhi high court that custodial interrogation of the veteran Congress leader was required in the INX media case.