The Singapore Customs officers arrested the four men last Saturday with 14,999 cartons of contraband cigarettes.
They had evaded SGD 1.1 million of duty and Goods and Services Tax on the cigarettes.
Mogan Ayawoo, 37, Kasidesan Ramansantiran, 26, and Manirajan Abimanan, 25, were seen moving the pallets from a 40-feet container into a warehouse unit, officials said.
The Customs officers then raided the unit and found the cigarettes concealed in specially constructed hollow spaces in the pallets.
The officers had kept a watch on the container which arrived at the import scanning station last Friday.
They also arrested ringleader Thiru Chelvam Krishnasamy, 33, later.
Singapore Customs said investigations showed Thiru had sought the assistance of the other three to move the contraband cigarettes into the unit.
Thiru was sentenced to three years in jail, while the others were sentenced to 34 months in prison.
