The Health Sciences Authority (HSA) said on April 25 that it confiscated 5,356 devices, known as e-cigarettes or "vapers," last year, almost three times the seizures in 2012. The figure compares with only 10 such seizures in 2009.
The battery-powered devices deliver a puff of nicotine vapour in a variety of possible flavors, minus many of the toxic chemicals present in a cigarette.
The 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 said 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 (US$7,951).
Singapore is one of the costliest cities to buy conventional cigarettes, with a pack of Marlboros costing around Sg$13 ($10.30).
By Ruchi Singh
reporter
Park Sae-jin
swatchsjp@ajunews.com