The Income Tax department will on Monday question the Union Bank of India CMD why the bank did not do the due diligence while accepting deposits of more than Rs 991 crore from an alleged frontman of former Jharkhand Chief Minister Madhu Koda.

Sources said the bank’s Chairman and Managing Director M V Nair had been summoned by the tax sleuth’s Mumbai office, accusing the bank of being negligent and not acting when crores were being deposited.

According to the guidelines set by the Reserve Bank of India, banks are supposed to raise an alarm or ask for specific details if more than Rs 50,000 is deposited in an account, the sources said.

Manoj Punamia, the alleged Koda frontman, had deposited more than Rs 991 crore in the Union Bank account of Mumbai-based Balaji Bullion Bazar during 2008 and 2009.

Out of Rs 991 crore, nearly Rs 500 crore were deposited in the account in cash.

Koda is said to have been operating through Binod Sinha, Manoj Punamia and Sanjay Chaudhary who are also stakeholders in the Balaji Bullian Bazaar.

The former chief minsiter of the mineral-rich state is accused of amassing illegal wealth worth more than Rs 2,000 crore and has more than 70 bank accounts. Various agencies are investigating into the scam.