Thaweeluck, 37, and Phromphiram, 23, (last names withheld) were arrested on Thursday as they trying to hit the poor creatures with tranquiliser darts.
Wat Khao No, a mountainous tourist attraction in Nakhon Sawan’s Banphot Phisai district, is famous for its long-tailed macaques.
The suspects reportedly confessed they were planning to sell the monkeys to restaurants in neighbouring countries, and apparently expected to be paid up to 100,000 baht per macaque.
Officials shifted nine tranquilised macaques to a shelter near Wat Khao No, but one succumbed to the effects of the tranquiliser and another was killed by a dog. Locals said the dog got to the monkey because someone had left the cage open.
The rest of the monkeys were eventually released into the wild on Friday morning.
A vendor selling food for monkeys at Wat Khao No said the number of macaques had dropped sharply in the past few years because smugglers have been capturing and selling these creatures. He said that sometimes the parents were taken away, leaving the babies to starve to death.
Suwan Khamenkhetkarn, a Banphot Phisai resident, said the mountain once housed more than 100,000 monkeys, but now there are fewer than 10,000 left due to these smuggling gangs. She said officials should boost patrols around the area and arrest these smugglers before all the monkeys are gone.