Ahead of the Lok Sabha polls, search operations by income tax sleuths are underway on Wednesday at the residence of Trinamul Congress leader Swarup Biswas who is the brother of a West Bengal minister, an official said.

The raids, which are continuing for more than 12 hours, are part of an investigation into alleged tax invasion by two real estate companies, he said. "Sleuths of the Income Tax Department's investigation wing are conducting search operations at five locations related to Swarup Biswas in the city. Some of the locations where the search operations are going on are in New Alipore and Behala areas," the I-T official told PTI. Swarup Biswas is the brother of minister Aroop Biswas.

The search operations are in connection with a "probe into allegations of tax evasion and possession of disproportionate assets by the two realty groups", the official said.

During the investigation, the existence of shell companies came to the notice of the sleuths, he said, adding that the premises of officials of the two real estate firms are also being raided.

The search operations started around 7 am, he added.

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