Asserting that there was "no collateral purpose" behind its action, a late night press release issued by the CBDT in Delhi said the searches were based on "credible information of tax evasion" and "financial irregularities".
The CBDT said while certain "incriminating evidence indicative of tax evasion and financial irregularities have been recovered during the ongoing investigation, no political person or its family member are today shareholders or directors of the companies searched or surveyed by the Income Tax department."
They said while the I-T had undertaken the action on charges of suspected tax evasion by these firms, the ED was a part of the searches in connection with their investigation under the provisions of the Foreign Exchange Management Act (FEMA).
Despite repeated attempts Karti was not available for comments.
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Soon after reports of the searches were out, Chidambaram accused the government of a "malicious onslaught" launched by it against his family and said if it wants to target him, it should do so directly and not harass friends of Karti.
The senior Congress leader said he was travelling and he
has been informed about searches conducted on certain firms in Chennai allegedly linked to his son.
"We have made it clear, repeatedly, that no member of my family has any equity or economic interest in any of the firms that are being targeted.
"They are companies that are professionally managed and are capable of answering any questions that may be put to them by the authorities. I condemn the attempt to link them to my son and harass them on that ground," he said.
"Orders in his case were apparently passed during the term of my predecessor. He met me and wanted me to intervene in his favour. I declined and I told him that I cannot reverse orders that were issued during the term of my predecessor.
"The change of government has given him an opportunity to misuse his powers to harass my son and his friends," he said.
The searches and surveys on a group based in Chennai and Tiruchirappalli and another private limited company in Chennai have been conducted strictly as per provisions of the Income Tax Act, the CBDT said.
"Disclosure of information respecting assesses is prohibited except as provided in section 138 of the Income-tax Act, 1961," it said.
The investigation wing of the Income Tax department in Chennai has been conducting probe and as part of it, searches under section 132 (search) and surveys under section 133A (surveys) of the Income-tax Act, 1961 are being conducted at the residential and business premises of the key functionaries of the group.
"Certain incriminating evidence indicative of tax evasion and financial irregularities have been recovered during the on-going investigation. Further action as per law will follow," it claimed.