The illegal practice, known as "cryptojacking," which sees criminals use others' computers for "crypto-mining," can leave victims with slower computer responses, overheating devices and high electricity bills.

Police said the number of worldwide"cryptojacking" cases this year was four times than that of last year.

Cyber Security and Technology Crime Bureau senior superintendent Raymond Lam Cheuk-ho said the latest case was uncovered during operation "Zestbold" between September and November.

Though police had only identified several "cryptojacking" cases in Hong Kong, Lam said more similar cases will only be a matter of time.

He added 2,486 "zombie" devices - devices hijacked by hackers for launching cyberattacks - were seized.

Among the devices, some were houseware, such as security cameras, routers, thermometers and printers.

Cybersecurity provider Radware's Asia Pacific and Japan vice-president Yaniv Hoffman said as a financial hub, Hong Kong was particularly vulnerable to "denial-of-service" attacks, where criminals temporarily or indefinitely make network resources unavailable to certain users. There was a significant increase of more than 40 percent in the first three quarters of this year compared to the same period last year.

To avoid becoming targets of cyber attacks, Hoffman reminded the public to update anti-virus software, not to click on links in suspicious emails and change passwords regularly. Most importantly, they must back up data.

Hong Kong Computer Emergency Response Team Coordination Center Frank Chow Kai-fat called on enterprises to stay alert to "ransomware" - malicious software used to extort users for money - which sees medium enterprises lose HK$300,000 on average.

Police recorded 13,163 cybercrime cases in the first 10 months of this year - a 24 percent rise from the same period last year - with losses amounting to HK$2.4 billion.