Police are stepping up publicity efforts against fraud after the number of deception cases in Hong Kong went up by 6.2 percent to nearly 20,000 in the first half of the year, incurring losses of HK$4.4 billion.

But instead of the elderly, the force is now actively reaching out to young people after noticing a demographic shift in victims.

Of all fraud cases between January and June, 1,605 involved victims who fell prey to swindlers claiming to be customer service representatives of online platforms such as Taobao and WeChat.

That number shot up to 1,111 in July alone.

More than one-fifth of those victims were aged between 18 and 29, compared with only seven percent who were 70 or above.

"It's because WeChat Pay and Taobao are commonly used by young persons, and they are the tech-savvy generation," said senior superintendent Tsang Nga-sze of the Commercial Crime Bureau.

In one of the cases, a 50-year-old clerk lost hundreds of thousands of dollars to a swindler posing as a WeChat representative last month.

He was told by the fraudster that he had subscribed to an insurance scheme with an annual fee of HK$70,000, and the plan would be renewed automatically if he didn't complete the cancellation process within that day.

Following the scammer's instructions over the phone, he transferred a "guarantee payment" to the swindler, in a bid to verify his identity.

"During the process, the scammer sent me some links with bank logos on it, and also [showed me] their staff card, which made me believe that the fraudster was a genuine WeChat representative," the victim said.

He only realised he had been conned after he was ordered to set up a virtual bank account, apply for a loan and then transfer all the money to a designated account.

Police warned that September and October are peak months for mainland students to get scammed.

"Usually, scammers will use the excuse that their visas have some issues because they are involved in some investigations," said superintendent Theodora Lee.

"As they are new to Hong Kong, and really want to study or work here... they will believe that they are the true officials from mainland China... and make relevant transfers."

The force emphasised that the public should ignore calls and messages involving money, or asking for personal details.