A spokesperson of the Central Bureau of Investigation (CBI) told the BBC that the agency was conducting searches in the southern city of Chennai (Madras).
The CBI is probing investment clearances given to a firm during Mr Chidambaram's tenure.
He said the government was using the raids to try to "silence his voice".
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CBI spokesperson RK Gaur said the agency was also conducting raids in other cities like Mumbai, Delhi and Gurgaon.
Mr Chidambaram, who served as finance minister until his Congress party was voted out of power in 2014, said the CBI was targeting him because of his writings.
The former minister often criticises Prime Minister Narendra Modi's policies in his speeches and articles.
He said every case during his tenure was "processed according to law".
The Congress party said the raids were "a fishing expedition launched by the Modi government against Mr Chidambaram".