Official sources said in Delhi that the searches were spread across Mumbai, Delhi, Chennai, and Gurugram.
The raids are also taking place at the Nungambakkam residence of P Chidambaram in Chennai, a senior police official said in Chennai.
Unconfirmed reports said the raids were also on at Karaikudi, the hometown of Chidambaram.
The agency has yesterday registered a case regarding Foreign Investment Promotion Board (FIPB) clearance given to INX Media, run by its directors Indrani Mukerjea and Peter Mukerjea, in 2007 which it is alleged that favours were given when P Chidambaram was the Finance Minister.
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It has levelled the charges of criminal conspiracy, cheating and taking gratification by corrupt or illegal means, to influence public servant and criminal misconduct.
Asked about the raids, the former union minister said, "You should have called your CBI friends...Should I stop writing ? (against the government)."
"I mean...(this is) absolute nonsense," Chidambaram told PTI adding he was not in Chennai.
He also said there are no allegations against him