Some customers were still unable to make transactions on DBS' website and mobile app for the third day on Thursday morning, even though the bank said services were returning to normal late on Wednesday night.
In a Facebook post at 10.35pm on Wednesday, DBS said: "Please be informed that our digital banking services are returning to normal. We are monitoring the situation closely to ensure all services run smoothly. Thank you for your patience."
Customers said they could log in to its digibank online platforms on Thursday morning, but many still could not make transactions or view past ones.
"I can log in now. But I cannot view my credit card transactions. Every click to card transaction is quickly refreshed back to main dashboard summary page," said Facebook user Jack Tan in a comment at about 7.40am on DBS' post.
Another Facebook user, Ms Allison Teo, commented at about 8am: "Able to log in, but it hangs and not able to click on any icon."
The bank replied to several customers, urging them to restart their devices and log in again.
Reacting to the bank's worst outage in more than a decade, the Monetary Authority of Singapore (MAS) said on Wednesday evening that it would consider taking "supervisory action".
"This is a serious disruption and MAS expects DBS to conduct a thorough investigation to identify the root causes and implement the necessary remedial measures," said Mr Marcus Lim, MAS' assistant managing director of banking and insurance. "MAS will consider appropriate supervisory actions following the investigation. MAS expects all financial institutions to have systems and processes to ensure the consistent availability of financial services to their customers."
Under the central bank's regulations, financial institutions must ensure that the total unscheduled downtime for critical systems affecting services for customers does not exceed four hours within any 12-month period.
The Straits Times