Criminal gangs from Cameroon and Colombia are also under close watch, they say.
Teams of officers staged a series of raids that resulted in a total of 2,274 arrests between June 1 and June 14, Pol Maj Gen Natthawat Karndee, commander of Immigration Division 4, said at a briefing in Khon Kaen on Saturday.
Of the suspects, 622 foreigners entered the country illegally, 31 overstayed their visas, 73 were working without permission, 16 were wanted on arrest warrants, 1,245 committed other offences, and 287 had been refused entry, he said.
Immigration police also joined forces with Thap Lan National Park officials to arrest 18 suspects — 15 Cambodian nationals and three Thais — on charges of illegally cutting protected phayung (Siamese rosewood) trees in the forest in Nakhon Ratchasima.
Immigration police in Nakhon Phanom, Ubon Ratchathani and Khon Kaen reported the arrests of Vietnamese and Indian suspects who entered the country illegally using fake passports. They are also suspected of providing illegal money lending services at high interest rates, said Pol Maj Gen Natthawat.
The agency, he added, has also been keeping a close watch on Colombian and Cameroonian criminals who have fled to the country. Some had committed offences in Thailand such as snatching bags and committing thefts and home break-ins. Some Cameroonian gangsters carried weapons, he added.