The customs spokesman for the Bali and Nusatenggara regional office, Wachid Kurniawan, said the suspects were arrested separately since last month upon arrival at the airport.
He said the Singaporean woman was captured Nov. 14 after immigration officer found a small plastic bag with 0.35 gram (0.01 ounce) of cocaine inside her passport, while the Chilean man was nabbed two weeks later with 77.26 grams (2.7 ounces) of liquid methamphetamine in his black suitcase.
The Hong Kong man was arrested Dec. 4 with 3.2 kilograms (7 pounds) of crystal methamphetamine in his luggage, and his 19-year-old fellow Hong Kong national was captured last week with 4 kilograms (8.8 pounds) of crystal methamphetamine wrapped in four branded pet food packaging in his luggage, Kurniawan said.
Indonesia has extremely strict drug laws, and convicted smugglers are sometimes executed by firing squad.
More than 150 people are currently on death row, mostly for drug crimes. About one-third of them are foreigners.
In May, a Frenchman was sentenced to death on Lombok, an island next to Bali, for smuggling 3 kilograms (6.6 pounds) of ecstasy before a higher court commuted his sentence to 19 years in prison.
Last month, a court in Bali sentenced two Thais to 16-year prison terms for smuggling 1 kilogram (2.2 pounds) of methamphetamine.