SINGAPORE - THE Monetary Authority of Singapore (MAS) said Thursday night that some policyholders of Prudential Assurance Company Singapore encountered erroneous deductions from their bank accounts.

Customer accounts of multiple banks were affected, the MAS said, adding that this incident was due to an operational lapse, not a cyber attack.

MAS has directed Prudential and its payment bank, Standard Chartered Bank Singapore to effect the return of customer funds without delay, to keep customers updated, and to investigate the root cause of the incident.

"We take a serious view of such operational lapses and will take follow-up supervisory measures where appropriate," it said.

A check on Prudential Facebook account indicated that policyholders had excess amount deducted from their accounts.

"We are aware that a number of you have experienced a GIRO deduction in excess of your insurance premiums or a failed GIRO deduction. We have investigated the matter and found that this is due to a technical error. This was not a cyber attack. We are very sorry for the inconvenience caused," the Facebook page said.

"Please be assured that we are working actively to resolve the issue as quickly as possible, and together with our bank partner, intend to credit the relevant amount deducted back into your accounts within the next 24 hours. Any interest lost will be refunded and any erroneous charges will be reversed as soon as possible."