A total of 11,400 cartons of contraband cigarettes were seized by the Singapore Customs in two operations last week.
The total duty and goods and services tax (GST) evaded in both cases amounted to $1,061,340.
During the first operation, on Sept 4, officers raided a warehouse in a commercial building in Tuas View Place, after seeing three men moving green gunny sacks, suspected to contain duty-unpaid cigarettes, into the warehouse.
A total of 3,900 cartons of duty-unpaid cigarettes and a Singapore-registered truck, from which the duty-unpaid cigarettes were being unloaded, were seized.
Court proceedings against the three men, who are Singaporeans aged between 19 and 42, are ongoing.
Two days later, Customs officers conducted a second operation at an industrial estate in Depot Lane. Three Singaporean men between the ages of 25 and 55, who had transferred duty-unpaid cigarettes from a truck to a van, were arrested.
A fourth Singaporean man, aged 23, drove another van loaded with duty-unpaid cigarettes from Depot Lane to an open carpark in Seah Im Road before fleeing. He was arrested at Woodlands Checkpoint later that day.
This operation resulted in the seizure of 7,500 cartons of duty-unpaid cigarettes and three Singapore-registered vehicles - a truck and two vans - used to transport the contraband cigarettes.
Court proceedings against three of the men are ongoing, while the 55-year-old man is assisting Singapore Customs with investigations.
In a separate incident, Immigration and Checkpoints Authority (ICA) officers uncovered 180 cartons and 1,041 packets of duty-unpaid cigarettes in a car at Tuas Checkpoint on Saturday.
The cigarettes were hidden in various modified compartments of a Singapore-registered car.
According to a Facebook post by ICA, the car was driven by a male Singaporean, 35, who was returning to Singapore with his wife and their seven-year-old son.
The case has been referred to Singapore Customs, and court proceedings are ongoing.
Buying, selling, conveying, delivering, storing, keeping, having in possession or dealing with duty-unpaid goods are serious offences under the Customs Act and the GST Act.
Those caught can be fined up to 40 times the amount of duty and GST evaded. They may also be jailed for up to six years.
Repeat offenders who are caught with more than 2kg of tobacco products will also face mandatory imprisonment.
Vehicles used in the commission of such offences can be forfeited.