Phone scammers who have conned people out of HK$77 million so far this year have fine-tuned their tactics so that they are able to manipulate number displays as calls from mainland officials, police said.
There have been 84 phone deception cases related to fake mainland officials since the start of the year, including a case in which around HK$58 million was scammed from a retired businessman last Friday.
There were 1,423 cases related to fake mainland officials last year 60 times more than in 2014 involving around HK$290 million.
Chief inspector Lam Cheuk-ho of the Kowloon East regional crime unit said: "The con artists have already fine-tuned their tactics to make the scam become more convincing.
"They can make their incoming call number appear the same as those of real mainland officials, so the victims would not question their identities."
He said police have been aware of the trick since October, and they hope a new mobile app being developed in cooperation with City University to help identify suspicious call numbers will end it.
"I hope it can be launched in two months," Lam said.
Of the 84 victims, half were Hongkongers, and the rest new immigrants, exchange students and workers from the mainland.
"Most of them have heard about the scam, but do not understand much about the details and tricks," Lam said.
Around 20 percent of the victims were housewives who did not pay much attention to current affairs and browse online, he said.
"That's why, instead of just promoting through the news media, police have also been distributing leaflets in housing estates to educate them on how to avoid being cheated."
Police said victims would first receive a call from a person claiming to be a courier company staff and saying that a parcel they mailed contained illegal documents.
If the victims denied this, the call would be transferred to "mainland police," who would then collect "oral evidence" and ask for a list of their financial assets, including car insurance and property.
Some victims who questioned their identities over the phone would be provided with a number for a legitimate mainland public security official or office. Usually victims would verify the number online. After that the con artists would ring back and ask them to deposit money into a mainland bank account to "prove their innocence."