To get contraband items into Singapore, smugglers are trying everything from hiding duty-unpaid cigarettes in luxury cars to squeezing them into decorative stools.
In one instance last August, more than 2,180 cartons of duty-unpaid cigarettes were seized from boxes declared to be containing children's play mats.
Announcing its annual statistics in a report yesterday, the Immigration and Checkpoints Authority (ICA) flagged smugglers' new tactics. It said these methods are "a cause for concern, especially in the current security climate", as they could be adopted by terrorists bringing dangerous materials into the country.
The month after the play mat incident, ICA officers found 347 cartons and 530 packets of contraband cigarettes in parts of a new luxury car. The Straits Times understands that smugglers have used Lexus, Volvo and Mercedes-Benz cars in the past.
Still, the number of contraband cases detected has dropped by 8 per cent, from 95,677 in 2015 to 88,050 last year.
Commissioner Clarence Yeo said that ICA "remains determined and steadfast in securing our borders".
His remarks come in a climate of heightened security.
In February last year, ICA officers at the Woodlands Checkpoint refused entry to four Indonesians - three men and a 15-year-old - at the arrival bus hall.
They were suspected of being en route to the Middle East to join the Islamic State in Iraq and Syria (ISIS) terror group. All four were subsequently handed over to Indonesian police.
"As the nation's first line of defence, ICA will continue to conduct stringent checks on people, goods and conveyances while enhancing border clearance through innovation, collaboration and partnership," said Mr Yeo.
Number of contraband cases detected in 2015.
Number of contraband cases detected last year.
Innovative tactics include the use of biometrics technology to more definitively identify a person and enhance security clearance.
The use of technology, such as biometrics in automated systems, also allows the ICA to redeploy officers to focus on high-risk travellers.
Dr Rohan Gunaratna, head of the International Centre for Political Violence and Terrorism Research, said: "Criminals and terrorists are becoming smarter.
"They are learning with every detection and disruption."
Mr Edwin Tong, deputy chairman of the Government Parliamentary Committee for Home Affairs and Law, said: "Given that we are an island with very porous borders, the ICA plays a very big role.
"Instead of cigarettes, you could have explosives, chemicals or drugs, which could be very difficult to detect once they cross our borders. You need very little space to smuggle chemicals or weapons."
Meanwhile, ICA figures showed that fewer illegal immigrants and overstayers were arrested last year, with the numbers dipping by more than 30 per cent.
Reflecting a downward trend in recent years, the number of illegal immigrants caught fell from 310 in 2015 to 217 last year, while the number of overstayers dropped from 1,591 in 2015 to 1,061 last year.
ICA said it adopts a "multi- pronged approach to deter, deny and detect" such offenders, adding that it will continue to work closely with the police and Manpower Ministry to enhance enforcement.
Fewer home owners and employers were found giving lodging and jobs to immigration offenders last year, after a 59 per cent spike in 2015.
Last year, 306 people were arrested for harbouring immigration offenders, down from 416 the year before, while the number of errant employers caught dropped from 91 in 2015 to 45 last year.
Besides ramping up community engagement, ICA said it will remind home owners and employers to conduct checks on the immigration status of foreigners before renting their premises or offering jobs.
Fewer people were convicted over marriages of convenience as well, with the number dropping from 64 in 2015 to 43 last year.