The Central Bureau of Investigation (CBI) is conducting searches at the residences of former Union minister P Chidambaram and his son Karti Chidambaram.
Issuing a statement, Chidambaram said the government is using the CBI to target his son and his friends.
He also alleged that the government is trying to stop his voice but asserted that he will not be silenced.
''FIPB approval is granted in hundreds of cases," the statement said.
"Every case was processed according to law and approval was granted or refused in accordance with the recommendations of the FIPB consisting of five secretaries to the Government of India."
Sources have said that the raids were conducted in connection with the Aircel-Maxis probe. Recently, the Enforcement Directorate (ED) had searched Chidambaram's house.
Tuesday's development comes almost a month after the CBI informed, according to reports, the Supreme Court (SC) that it was investigating Chidambaram's role in the alleged illegality of permitting Malaysian firm Maxis to acquire 100 per cent stake in Aircel directly and indirectly through foreign direct (FDI) investment in 2006.
Bharatiya Janata Party (BJP) leader Subramanian Swamy moved the SC seeking a probe into Chidambaram's alleged role in illegally permitting Maxis to acquire 100 per cent stake in Aircel. It has been claimed that this was done without following the procedure of sending the FDI proposal to the Cabinet Committee on Economic Affairs (CCEA) despite the total worth of the deal being more than Rs 600 crore.
On Tuesday, in Chennai alone, eight places, including Chidambaram and his son's house, are being searched. Chidambaram's residence at Sivaganga in Southern Tamil Nadu has also been searched.
In April, the ED had filed a status report in a sealed cover before the SC on the status of its investigation in the money laundering case related to the Foreign Investment Promotion Board (FIPB) approval of the Aircel-Maxis deal, including the role of former finance minister P Chidambaram. The investigations under the Prevention of Money Laundering Act are going on in respect of the FIPB approval given to the Aircel-Maxis deal by the then finance minister, wherein foreign inflow was around Rs 3,500 crore whereas as per government policy and FIPB guidelines, the competent authority was the CCEA for any inflow above Rs 600 crore.
BJP's Swamy has been alleging Chidambaram's role in the deal, and the SC, in February, gave him two weeks to bring out credible material to prima facie prove Chidambaram had granted FIPB clearance to the Aircel-Maxis deal deliberately in 2006. The question was also whether Chidambaram was aware that the limit was Rs 600 crore.
Chidambaram responded to the allegation earlier, saying that he granted approval to the deal "in the normal course of business".
"In the Aircel-Maxis case, taking into account the face value of the foreign investment, the FIPB submitted the case to the finance minister and sought approval," he said. As the finance minister, he said, he granted approval in the "normal course of business".
In April, the ED had also served a notice to Vasan Health Care Pvt Ltd (Vasan) and its promoters for Foreign Exchange Management Act (FEMA) contraventions to the tune of Rs 2,262 crore. The ED also served a notice to Advantage Strategic Consulting and Chidambaram's son Karti Chidambaram for Rs 45 crore for FEMA contraventions in the sale of Vasan Shares to overseas investors.