The Thai Chamber of Commerce has voiced concerns about the low number of worker registrations in the service, construction, farm and fishery sectors.
Chamber vice-chairman Poj Aramwattananont warned there will be swift legal penalties against workers if they fail to register before the Aug 7 deadline.
He said businesses and employers are making their best efforts to get workers to meet the registration and attain legal working status. Once the deadline lapses, they could do nothing to help the workers who refuse to register, he said.
Employers had managed to get deadlines in previous migrant worker registration rounds extended on many occasions.
He said low turnouts were in the labour groups of domestic helpers and construction, farm and fishery workers.
Mr Poj said the problem might stem from a misunderstanding of some employers, such as vendor stall owners, who thought they were small-scale businesses who did not have to secure the registrations for their migrant workers.
Between July 24 and Aug 3, employers have filed 113,374 registrations for their migrant workers nationwide.
Department of Employment deputy chief Sombat Niwetrat said a total of 20,867 workers in small retail and vending businesses and 28,983 domestic helpers have registered nationwide so far.
Bangkok, the country's biggest employer province, has recorded 84,957 migrant worker registrations, followed by Samut Prakan with 22,974 registrations and Rayong (19,821 registrations), Pathum Thani (19,571 registrations) and Chiang Mai (16,325 registrations).
Director-general of the Employment Department Waranon Pitiwan said yesterday the department estimates that up to 1 million illegal migrant workers will report to authorities during the July 24-Aug 7 registration.
He insisted the Labour Ministry would not extend the deadline and the process of verifying the employment would start on Aug 8 and is expected to be completed within 30 days.
According to Mr Waranon, each centre is able to interview about 500 migrant workers per day and after the employment status is verified, the next step is nationality verification.
He said Myanmar and Cambodian authorities will send their officials to process national verification in Thailand at One Stop Service Centres. Those who complete the verification stage will be given Certificate of Identity (CI) papers.
The CI papers are necessary for the visa applications and, after they complete physical health examinations and pay health insurance, they will be issued work permits.
He said the entire process takes a day. As for Lao migrant workers, after the verification of employment status is completed, documents will be given to the migrant workers for them to contact the Lao embassy in Thailand.
The workers will then receive travel papers to return home where they will be asked to apply for work under an MOU, he said, adding that Lao authorities will conduct nationality verification for Lao workers who have pink cards only.
According to labour officials, expenses for Myanmar migrant workers are about 2,360 baht per head.