Nearly 60 Cambodian nationals were rounded up in Sa Kaeo's Ta Phraya district as they headed to work in the country illegally.
The arrest of the 59 Cambodians was part of a wider operation led by the Burapa army task force to crack down on people slipping into the country across the eastern border.
The operation, ordered by the task force commander Maj Gen Tharapong Malakham, was also mounted to keep out goods, including farm produce, smuggled into the country during the Covid-19 pandemic.
The Cambodians were intercepted by soldiers on patrol in Ban Khlong Paeng in tambon Thap Sadet early yesterday.
The suspects, 25 of whom were women, failed to produce passports or other travel documents. They were charged with illegal entry.
Officials said the suspects came from Poi Pet, in Banteay Meanchey province. They entered Thailand through the porous natural borderline between border surveillance points 14 and 15.
They were waiting to be picked up by a trafficking gang who promised to take them to various provinces to work. The suspects told the authorities they paid the gang 3,000 each as a brokerage fee.
The Cambodians were remanded in custody at Ta Phraya police station.
In Tak, officials arrested 12 Myanmar and three Chinese illegal migrants in Phop Phra and Mae Sot districts yesterday.
They had crossed the border in Moo 1 village of tambon Valley in Phop Phra district overnight and had no travel documents.
In Mae Sot, police arrested three Chinese nationals -- Chen Siding, 26, Shena Wenham, 25, and Liu Mingus, 25 -- after stopping a taxi at a checkpoint in Ban Huai Hin Fon in tambon Mae Pa.
They had overstayed their visas by 106 days, an official said.
Meanwhile, in Nong Khai, an African man who once played football for a club in Rayong was nabbed for overstaying his visa.
Eric Ridwane, 32, from Ivory Coast, was apprehended on Monday. He first gave police a false name, prompting investigators to run a biometric check which revealed his true identity.