About 280 people have died in India's south after Tamil Nadu state was engulfed by torrential rains last week.
India's banks will work on Sunday to help residents left without food, power and money in the flood-hit southern city of Chennai and surrounding areas.
India's fourth largest city was swamped by torrential rains - the heaviest in a century - during the past five days, and the government has asked banks to restore basic services and supply cash machines as swiftly as possible, replenishing cash by boat or providing mobile ATMs if necessary.
In a statement late on Saturday, the Reserve Bank of India, the country's central bank, said it would remain open to support bank transactions and help supply cash to local lenders.
About 280 people have died across Tamil Nadu state since it was hit by torrential rains on December 1 that left large sections of capital Chennai under up to (2.5 metres of water, and trapped people on rooftops with no communication.