The CBI sources said the searches were carried out in connection with an FIR registered against deputy commissioner Navneet Kumar, appraiser Vicky Kumar and a private person Mohammed Naseeruddin.
The deputy commissioner and the appraiser have already been suspended by the customs department.
The searches are spread at seven locations in Kolkata, one in North 24 Parganas in West Bengal and one location in Bihar, they said.
The case pertains to alleged illegal imports of goods by customs officials by evasion or part evasion of duty, thus causing loss to the government, they said.