Permanent secretary Jirasuk Sugandhajati said on Tuesday that the Ministry of Labour was printing leaflets in the Myanmar, Lao and Cambodian languages and would distribute them to workers from these three countries.
The leaflets would reassure them the ministry was not indiscriminately prosecuting alien workers.
He hoped tbhis would allay fears and end the exodus and the resulting labour shortage in Thailand, especially in factories and construction sites.
Mr Jirasuk said he would go to Chon Buri province on Wednesday to discuss the campaign to send the message to alien workers in eastern provinces of Thailand - particularly Chanthaburi, Rayong and Trat. He will talk to labour-related authorities in the East, where more than 100,000 Cambodian workers had already left Thailand.
He would be accompanied by Pravit Khiengpol, director-general of the Department of Employment.
Mr Pravit said foreigners who entered Thailand daily to work at local farms and returned home in the evening could continue to work without any concern.
However, authorities planned to require the legalising of alien workers in the construction sector. They must have passports and visas to work in Thailand, Mr Pravit said. He admitted this affected labour in the construction sector.
He also said legal and one-stop labour migrant services would be opened in Sa Kaeo, Chanthaburi and Trat provinces later this month. These provinces all border Cambodia.