The Department of Employment is aiming to tackle the growing problem of Thais travelling abroad to work illegally, especially in South Korea.
Arak Phrommanee, the department's director-general, said there had been an increasing incidence of Thais travelling to South Korea as tourists and then picking up jobs without the necessary paperwork.
Mr Arak said many of these Thais travelled to South Korea after being told they could secure employment first and then obtain a work permit later.
He issued a reminder that South Korea -- and in fact most countries -- do not allow foreigners to work if they only hold a tourist visa.
He said many such jobs are advertised online by people claiming to be overseas work agencies authorised by his department. This is simply not true, he said.
"When they [aspiring Thai workers] arrive, they are usually abandoned and forced to live illegally, and later arrested and eventually deported," Mr Arak said.
South Korea is the top destination for illegal Thai workers, while other popular countries include Bahrain, Sudan, Indonesia, Russia, the United Arab Emirates, Papua New Guinea and Japan, he said.
A source said South Korea is preferred because of the popularity of Korean pop culture and the fact that the wages there are typically much higher than those offered in Thailand for similar jobs.
Adding to the problem of Thais working illegally there is that most of them struggle to pass Korean language tests. Attaining Korean proficiency is a requirement under the Thai-Korean employment permit system, the source said.
Fewer than 20% of Thai workers applying for work permits in South Korea passed the language test, the source said.
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This resulted in the South Korean government lowering its quota for Thai workers, from 5,700 in 2013 to 5,400 in 2014.
The source said the would-be Thai workers often claimed the quality of teaching at Korean language schools preparing them to sit the test was poor.
The Labour Ministry has arranged for inspections to be carried out at those language schools. Meanwhile, the South Korean government has sent some native-speaking Korean teachers here to teach Thais on a volunteer basis, the source said.
Immigration Bureau chief Pol Lt Gen Natthorn Phrosunthorn revealed that South Korea deports more Thai travellers than any other country.
Last year, 28,750 Thai nationals were deported by South Korea's immigration authorities, he said.
Of this total, 8,656 were deported after being found to have overstayed their visas.
The remainder were kicked out or refused entry for unidentified reasons.
"The Foreign Ministry has to be informed about [the reason behind the deportations] so it can help resolve the problems," Pol Lt Gen Natthorn said.
"It's a waste of money for those Thai travellers denied entry to South Korea. Apart from that, it's a matter of dignity as well.
"As they didn't clearly specify why those people were denied entry to South Korea, we should be given clearer information on immigration conditions concerned so we can warn Thai people ahead of their travels."
The number of Thai people denied entry to, or deported from, South Korea last year was more than double the 2014 figure, from 12,564 to 28,750. In 2013, the figure was 9,972.
However, South Korea started allowing Thai tourists to visit visa-free for 90 days in late 2013.
Before, they they required visas for any duration of stay.
Only 31 South Korean nationals were denied entry to Thailand last year.