MUMBAI: Millions of customers of the State Bank of India were affected after its centralized server crashed rendering branches inoperational for most of Saturday. India's largest lender said it would keep all its 13,929 branches open on Sunday to make up for the inconvenience.

Customers were told that no transactions would be possible as the centralized servers were down. The problem was compounded as it happened a day after the half-yearly closing. It was also the first day of the month when most people withdraw their salaries and the eve of a festival on Sunday, which saw a renewed demand for cash. Most ATMs were also not functioning since morning.

"The problem has been sorted out and we have asked our branches to remain open until all customers are serviced. In addition we are keeping all our branches open on Sunday," SBI Chairman Pratip Chaudhuri said.

"The speed of the server which normally completes 1,700 transactions per second dropped to 400 per second which led to the problem," Chaudhuri said. Officials suspect that problem had something to do with the half-yearly closing of accounts on Friday. "We are investigating the problem," Chauduri said.