The Central Bureau of Investigation (CBI) has conducted searches at 13 locations in West Bengal and Karnataka and registered an FIR in connection with Rs 820 crore worth of suspicious IMPS transactions that "mistakenly" landed in 41,000 UCO Bank account holders in November this year.

The multiple cities where search operations were conducted, continuing till late night Monday, included Kolkata and Mangalore. The state-owned UCO Bank is headquartered in Kolkata.

The CBI action came following the FIR that was registered on a complaint from UCO Bank against two support engineers working with the bank and other unknown persons. 

It alleged suspicious Immediate Payment Service (IMPS) transactions amounting to approximately Rs 820 crore.

Between November 10 and 13 this year, over 8.53 lakh IMPS transactions took place in which Rs 820 crore originating from 14,000 account holders of seven private banks landed in the 41,000 accounts of UCO Bank customers, the investigating agency said.

The transactions were "mistakenly" posted in the accounts despite originating banks registering "failed transactions", it said.

"Consequently, an approximate sum of Rs 820 crore allegedly found its way into UCO Bank accounts without proper debits from the originating banks' account holders," it added.

Several UCO Bank customers withdrew the amount "benefiting wrongfully" from the transaction, it said.

Last month, UCO Bank had said that it recovered Rs 649 crore or 79% of the amount erroneously credited to some accounts of the bank.