The Immigration and Checkpoints Authority (ICA) has foiled an attempt to smuggle 1,500 packs of e-cigarette refills transported by a Malaysia-registered lorry.

The haul was discovered on July 3 after checks and inspection of the lorry uncovered five suspicious boxes deep within its cargo.

The case has been referred to the Health Sciences Authority for further investigation.

"This method of concealment is a cause for concern as similar methods may be used by people with ill intent to smuggle security items into Singapore," said the ICA in a Facebook post last Thursday.

"The ICA will continue to conduct security checks on passengers, goods and vehicles so as to safeguard Singapore's security," it added.

It was reported in October last year that Singapore's e-cigarette sellers have become more creative in selling vaporisers here, with an "underground" network of stores and sellers operating to get vape refills from across the Causeway to customers here.

Singapore's laws have made it illegal to possess, purchase and use vapes here since February 2018.

Those found guilty of any of these offences can be fined up to $2,000.

Penalties for those who buy vaporisers online and have them shipped to Singapore for personal use are much heftier; those found guilty of the offence can be fined up to $10,000 and jailed for six months.

Repeat offenders could be fined $20,000 and jailed for a year.