"I belong to the Opposition party. Let the government misuse the ED. I shall neither bend nor break and I shall continue to speak and write," Mr Chidambaram, 72, said in a statement on Saturday.
The Congress leader said the raids were a reaction to the notices sent out by the Supreme Court, which heard the appeal of his son on Friday. Karti Chidambaram, a 46-year-old businessman and Congress member, had questioned the cases filed against him by the investigators.
Mr Chidambaram also questioned the agency's jurisdiction to investigate the matter.
"There is no FIR (First Information Report) in respect of a scheduled crime registered by any police or agency including the CBI," Mr Chidambaram said. "In absence of a scheduled offence, there are obviously no proceeds of crime and therefore the ED has no jurisdiction to probe the matter under PMLA (the Prevention of Money Laundering Act)," he added.
Congress spokesperson Randeep Singh Surjewala said the raids were part of a "continuing vicious vendetta unleashed by the Modi government against Congress and other opposition leaders".
The Aircel-Maxis case is linked to an approval granted by Foreign Investment Promotion Board to Aircel-Maxis in 2006, during Mr Chidambaram's tenure as the finance minister.
The agency said the finance minister could project proposals only up to Rs.600 crore. Bigger proposals are referred to the Cabinet Committee on Economic Affairs. In this case, the Rs. 3,500 crore proposal was cleared without an approval from the cabinet committee, the agency said.
The agency has said it is looking into the "circumstances" in which approval was given. Karti Chidambaram is accused of facilitating bribes. The agency said he has closed certain bank accounts and attempted to close others "to frustrate the process of attachment" under the PMLA.
With inputs from PTI