CBI sources said a major coordinated search operation at various locations -- including six in New Delhi and two in Mumbai -- was carried out on Thursday. Several offices of Finance Ministry and Commerce Ministry, residences of its officials and a well known Mumbai-based Chartered Accountant were covered.

The sources said a trove of confidential documents and Rs 60 lakh cash was allegedly recovered from the residence of the Chartered Accountant besides large number of electronic documents have been found on the laptop, tablets and hard disks recovered from the residence of officials and CA.

The sources said Chartered Accountant Khemchand Gandhi, Under Secretary in Department of Disinvestment and Grievances Ashok Kumar Singh and Section Officer in the Department of Economic Affairs Lala Ram Sharma have been detained by the agency.

It is alleged that the government servants were selling documents related to Foreign Investment Policies which are being floated in the ministries to Gandhi who in turn passed them on to big corporates for a price.

The sources said big names in banking, pharmaceuticals and realty business are under the scanner of the agency which CBI officials termed as "tip of the iceberg". All these groups under scanner have applied for foreign investments.

The sources said agency has registered a case of criminal conspiracy, theft under IPC and misuse of official position against the trio.

The departments which were searched on Thursday included Department of Economic Affairs and Department of Disinvestment in the Finance Ministry besides Department of Industrial Policy and Promotion in the Commerce Ministry.

The sources said suspected beneficiaries whose names have cropped during the interrogation of Gandhi and recovery of documents include HDFC Bank, Indusind Bank, Glenmark Pharmaceuticals and Novalead Pharmaceuticals among others.

The comments from these companies have been sought and are still awaited.

The sources said the racket was active for last two years and might have sold and influenced the policy of government regarding foreign investments in India.

"The Under Secretaries and Section Officers of ministries are custodian of policy documents and also the first movers of policy proposals. We suspect that they might be influencing the policies in favour of corporates. But that is a matter of probe," a senior CBI official alleged.

The sources said the agency was tracking the officials and the chartered accountant and on Thursday intercepted a courier in Mumbai in which an entire confidential file was recovered.

The courier was allegedly sent by Ashok Kumar Singh to Gandhi, the sources said.

They said by getting to know that a particular foreign investment policy was being floated in the government gave the beneficiary corporate groups a time window to prepare themselves for the policy when it finally gets enforced.

The sources said this case is separate from that probed by the Delhi Police as it was proper sale of documents via a CA to the corporate groups who have interest in the foreign investments.