Police on Monday warned people to watch out for suspicious pop-up alerts on their computers, to avoid falling prey to "technical support" scams.

Officers said 12 cases were recorded in the past two months, with total losses amounting to more than HK$17 million.

They said scammers send false system alerts to computers and pretend to be law enforcement agencies, before asking victims to call technical support and transfer money.

Superintendent Baron Chan from the force's cyber security and technology crime bureau said victims are usually foreigners and English speakers.

“Nowadays, the operation systems that we are using in most of our computers are Western-based. The language we use is mostly English, so that's why the scammers purport the scam alerts, they are mostly using English,” he said.

A 70-year-old retiree, who gave her name as May, said she lost around HK$10 million to fraudsters who posed as police officers and technical personnel at Apple.

“The alert seemed urgent and official and being accompanied by ongoing loud noise and flashing colours on the screen. It was a relief to be offered a solution to a computer security threat, so I called the number,” she said.

Chan advised people to install antivirus software and avoid calling any technical hotlines, adding that the force is taking steps to block such pop-up advertisements.

“If your computer displays some alert message, especially in full screen, you can try to press and hold the escape key on your keyboard or press control, alternate, delete at the same time to open the task manager to close the message, or even restart your computer to try to close the problematic pop-up windows,” he said.