The Income Tax (I-T) sleuths swooped on two major city-based builder groups and a business house manufacturing paper and paper boards on Wednesday. The search and seizure operation started since morning and is expected to continue till Thursday, said a senior I-T official.

The raids were carried out by 130 I-T officials along with police personnel at some 34 different premises in Ahmedabad, Mumbai and Delhi. The department said that the three business houses are closely connected groups and have inter-linked transactions.

A statement issued by I-T department claimed that large amount of unaccounted assets has been found and several lockers belonging to owners of these three groups have been sealed. These bank lockers will soon be made operational, the statement said.

Moreover, the I-T department has also claimed to have seized a large number of incriminating documents from the premises raided.

"As the operation goes ahead, we expect that more unaccounted money will be unearthed. But at this stage, it's difficult to say how much of the amount found is unaccounted," said the official.