Three people were arrested in connection with those cases. One was arrested on suspicion of passing counterfeit notes as genuine while the other two were arrested for obtaining property by deception.

Training notes are not genuine currency, have no security features and are said to be used mainly to train bank staff. The HK$1,000 bills look like the real thing except for three Chinese characters that say “practice coupon”.

The 1,693 training notes seized pushed this year’s total of forged HK$1,000 notes to 2,053.

The number of fake HK$500 notes seized more than quadrupled to 919 from 177 in the first four months of last year.

The other counterfeits seized were 404 HK$100 notes, five HK$50 ones, four HK$20 notes and 11 HK$10 ones.

“Most of the seized counterfeit Hong Kong banknotes are of low printing quality,” a force spokesman said.

Urging the public to be on the alert, police advised checking security features such as the dynamic shimmering pattern and windowed metallic thread used on Hong Kong notes.

According to the Monetary Authority, when a genuine bill is tilted the ring in the dynamic shimmering pattern moves correspondingly and the large and small rings on the metallic thread move correspondingly.

Aside from security features, Hong Kong currency is printed to produce a strong embossed feel, whereas the fakes have a smooth surface.

A police source said the quality of the fakes was so poor that people should be able to tell the difference by simply looking at or touching them.

Counterfeiters usually targeted convenience stores and taxi drivers to slip the fakes into circulation, he said.

“They use a fake HK$500 note to pay their taxi fare in return for the change,” he said. “They usually scrunch the bill, so that the cabby will not feel the smooth surface.”

The criminals often also struck at night, taking advantage of the poor light inside the taxi.

“We noticed counterfeiters have recently used fluorescent ink in their efforts to simulate some security features,” he added.

Another source said the counterfeit situation was not alarming as the fakes were a very small percentage of the total volume of genuine notes in circulation.

According to the authority, there were HK$614 billion in notes and coins in circulation as of March.

The source believed the quantity of counterfeit notes would decrease as electronic payment methods became more popular.

In Hong Kong, the production, circulation or passing of counterfeit notes as genuine is punishable by up to 14 years in jail under the Crimes Ordinance.

“On receiving a counterfeit banknote, you should immediately hand it over to the police or a bank and do not attempt to reuse it. Otherwise, you might commit the offence of passing counterfeit notes,” the police spokesman said.

In recent years, fraudsters have used training notes to swindle people in transactions related to cryptocurrency.

Last July, scammers who set up a fake cryptocurrency shop in Tsim Sha Tsui cheated a woman accountant of HK$1 million in digital currency using fake notes.

The woman, who wanted to exchange her cryptocurrency for cash, was served by a scammer who placed a stack of what appeared to be HK$1,000 notes on the counter.

The victim did as instructed and then transferred her Tether digital currency worth HK$1 million to a designated e-wallet account.

As soon as she completed the transfer, the scammer said he needed to go to the toilet and asked her to wait outside the shop, leaving the stack of cash on the counter.

She realised it was a scam when the man did not return and became uncontactable. She made a police report.

The Post learned that the stack of cash she saw on the counter had only two genuine banknotes at the top and bottom, and the rest were training notes.

In a similar case last month, a 35-year-old man reported being cheated of HK$1 million worth of Tether at a shop in Tsim Sha Tsui.

He saw a bundle of what appeared to be HK$500 bills which turned out to be hell notes, the ceremonial paper money burned in traditional Chinese rituals honouring ancestors or deities.

Police arrested three men and seized 3,000 hell notes in that case.

Two similar cases occurred in Tsim Sha Tsui and Hung Hom in 2022, when two people reported that they were swindled of HK$1.5 million each.