Income-tax officials have seized documents believed to be US Treasury bonds worth Rs 28,000 crore during a raid on the premises of a businessman in Tirupur district.
The raids were carried out on the residence of Ramalingam at Upputhurai Palayam village on December 31 night, official sources said.
The I-T action followed Ramalingam's reported application to the petroleum and chemicals ministries, seeking sanction to set up a Rs 1,000 crore crude oil refinery in Ramanathapuram district of Tamil Nadu.
They said some documents, which appeared to be US Treasury Bonds with a face value Rs 28,000 crore, were seized from his possession and further investigation was on.
Ramalingam is involved in the business of groundnut peeling equipment and used to make frequent trips to countries like Australia, Malaysia and Indonesia.
A year ago he had applied for sanction to set up the refinery in Thondi at a cost of Rs 1,000 crore.
The income-tax department had kept a close watch on the movement and activities of Ramalingam for the last few months culminating in the raids, they said.
The tax officials from Chennai and Combatore again returned yesterday and checked Ramalingam's accounts in various banks, the sources said.