An email scammer duped an American company into transferring US$3 million (HK$23.5 million) to a Hong Kong bank account last month, police sources revealed on Thursday, as the amount of money in cases handled by the force’s anti-fraud team surged to more than HK$2 billion.

In the latest case, police managed to freeze the swindled funds after the IT company reported the scam on April Fools’ Day. It was the biggest amount intercepted by the specialist fraud squad since it began operating last July.

The company made the erroneous transfer on March 28, after the scammer pretended to be a business partner. Staff realised they had been duped when they checked with the real business partner over the transaction.

The firm’s representative in Hong Kong made a report at a police station on April 1. Investigators froze the account with the help of a local bank and by Thursday were still trying to trace the recipient account holder.

One police source said the account holder might be a mainland Chinese resident recruited to come to Hong Kong and open an account with e-banking services.

The Post has reported that underground money changers have been helping international fraudsters set up accounts in the city and launder the proceeds of email scams.

The Anti-Deception Coordination Centre started work under the Commercial Crime Bureau on July 20 last year. Since then it has received about 800 requests to halt payments from victims of online and phone scams, totalling more than HK$2 billion.

It has helped to freeze about HK$300 million from more than 180 cases before the money was transferred out of the scammers’ bank accounts, mostly in Hong Kong.

More than half of the requests this year were from victims abroad or law enforcement agencies in other countries.

Over the past nine months, the calls to the centre involved 405 commercial email fraud cases, 156 social media deception cases including romance scams, 86 phone scams and 81 investment fraud cases.

While dealing with more than 16,400 calls to date to the centre’s 24-hour hotline, another source said, the team also prevented 61 callers from being duped.

The source said the number of reports of commercial email fraud and romance scams remained steady this year, but the number of phone scams decreased.

“We believe the drop in reports of phone scams is because mainland [Chinese] authorities mounted joint operations with overseas law enforcement agencies and closed down call centres [run by scam syndicates] abroad,” he said.

He warned the public to watch out for a newly prevalent WhatsApp scam, in which con artists hijack users’ accounts to cheat their contacts. Swindlers would fool victims into revealing their account verification codes and then use them to trick people on their contact lists.

The scam first came to the attention of police in November, but fewer than 10 cases had been reported then. Between December and February, more than 60 people fell victim to it.

According to official statistics, the number of deception cases dropped year on year by 2.3 per cent to 7,091 in 2017.