Dec 14 is the deadline for issuing temporary passports to migrant workers from neighbouring Cambodia, Laos and Myanmar as part of the nationality verification process.
From tomorrow, all illegal workers face being deported to their home countries, ending a two-decade regularisation process that has generally failed to ensure national, human and economic security.
Phumin Harinsut, vice-chairman of Thai Chamber of Commerce, said the business sector has urged Prime Minister Yingluck Shinawatra to extend the deadline.
The deadline was earlier postponed from June as the private sector could not verify the identification of migrant workers on time. These workers were employed in Thailand without permission.
About 530,000 foreign workers out of 880,000 needing verification had finished the process as of the end of November.
Labour-intensive sectors such as fisheries, seafood and construction face a labour shortage if migrant workers are deported.
Poj Aramwattananont, director of the Thai Chamber of Commerce, said most sectors except finance would be adversely affected if the verification deadline was not extended.
About 2-3 million migrant workers are employed in Thailand.
The 300,000 workers in the food-processing and frozen-food sectors are nearly all migrants. As the sectors are major exporters, the target of gross domestic product growth of 5% next year could be missed.
Atip Bijanond, president of the Thai Condominium Association, said the property and construction sectors have long had a labour shortage that will be worsened if illegal workers are deported.
That would affect state and private megaprojects because almost all construction workers are migrants.
Migrant advocacy groups are seeking the attention of the International Labour Organisation (ILO) chief during his current visit to Thailand.
The Samut Sakhon-based Migrant Worker Rights Network has prepared an open letter to the ILO today seeking its support for migrant rights in jeopardy due to the nationality verification deadline.
Labour activists estimate that 1.5 million undocumented migrant workers who did not complete the expensive and untransparent nationality verification process will become illegal workers.