An alert bank employee who acted on her instincts saved a customer from being ripped off to the tune of $32,500.

OCBC Bank service officer Chan Mee Lian, 43, knew something was amiss when a female customer came into the Jurong East branch and asked to make some baffling transactions.

The woman, 60, wanted to withdraw $20,000 and then transfer $32,500 from her savings account.

Ms Chan, who has worked in finance for 24 years, told The Straits Times that the woman had deposited the $20,000 in December last year as part of a Chinese New Year savings account promotion.

When she came in on Feb 12 to withdraw the funds, Ms Chan felt something was wrong, as the promotion required money to be kept in the account for at least six months.

She told the customer that there would be a $300 penalty for the NTUC FairPrice vouchers and special edition passbooks she had received as part of the promotion.

But the customer readily agreed to pay the penalty, which surprised Ms Chan - and raised her suspicions.

She inquired further about the purpose of the transactions.

"(The customer) looked like she was rushing and she was anxious. She refused to disclose the purpose," said Ms Chan.

Ms Chan was now convinced something had gone awry. She took the customer into a meeting room and consulted her privately.

The woman said she was transferring money to someone on Facebook, whom she claimed she knew.

But Ms Chan was still sceptical and advised the woman to consult family members.

"I told her if you still want me to go through with the withdrawal, you can come back to me," said Ms Chan.

A few hours later, the woman, accompanied by her daughter and son-in-law, arrived at the OCBC branch with a police report.

Ms Chan's suspicions proved valid. The police report said the woman befriended a Facebook user named "Tony Ng" two weeks earlier and he requested a $32,500 fee to process the delivery of some items.

He even sent the woman messages on WhatsApp, threatening to sue her if the money was not sent by 5pm that day.

This is not the first time an OCBC employee has helped to prevent a scam, said Ms Jean Oh, head of branch service and risk management, who noted that branch staff had prevented 22 suspected cases of unlawful transactions last year.

Correction note: This article has been edited for accuracy.