Despite stiff fines for distributors and smugglers, the Singaporeans are defying the ban on electronic cigarettes, as viewed by health authorities on Friday.
The Health Sciences Authority (HSA) said it confiscated 5,356 of the devices, known as e-cigarettes or "vapers", last year, almost three times the seizures in 2012.
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The battery-powered devices deliver a puff of nicotine vapour in a variety of possible flavours, minus many of the toxic chemicals present in a cigarette.
HSA said there was no conclusive scientific evidence to show that e-cigarettes help smokers quit tobacco use.
It added that health authorities are "concerned that e-cigarettes could potentially be a gateway to developing a smoking habit".
The agency says it watches websites and forums to monitor the illegal trade of e-cigarettes inside Singapore.
It said eight people have been prosecuted since 2011 for selling them.
Their import, distribution or sale is punishable by fines of up to Sg$10,000 ($7,951).
Singapore is one of the costliest cities to buy conventional cigarettes, with a pack of Marlboros costing around Sg$13 ($10.30).