The agency, along with the Income Tax department, had conducted multiple searches in Chennai and Bengaluru in this case in the recent past and the LRs, sources said, aim to obtain further details on these firms which the Enforcement Directorate is also probing for alleged contraventions of forex laws.
The sources said the latest probe also pertains to firms identified as Advantage Strategic Consulting Private Limited and Chess Global Advisory Services Pvt Ltd, where Karti had been a director, and few others for alleged violations of the Foreign Exchange Management Act (FEMA).
The LRs, they said, are expected to throw more light on the complex web of operations of these firms which are spread to over a dozen countries including UK and Singapore.
While Karti has denied any wrongdoing and has reiterated his cooperation with probe agencies, his father P Chidambaram had accused the government of a "malicious onslaught" launched by it against his family.
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"If the government wishes to target me, they should do so directly, not harass friends of my son who carry on their own businesses and have nothing to do with politics," he had said.
The agency is also expected to summon Karti for questioning in the case in the near future.
The probe agency, in January, had filed a charge sheet in the Aircel-Maxis deal that was a part of the 2G spectrum allocation case and had named former Telecom Minister Dayanidhi Maran, his brother Kalanithi, his wife Kavery Kalanithi and few other individuals and two companies as accused in the case filed under the provisions of the Prevention of Money Laundering Act (PMLA).
It had said the approval was given when Chidambaram was Finance Minister in 2006.