The Labour Ministry hopes the nationality verification (NV) of migrant workers will help improve the country's standing on the US human trafficking watch list.
The ministry feels the NV will help lessen the problems of human trafficking after it agreed to extend the process for another three months from Dec 14.
Employment Department director-general Prawit Khiangpol said the government was hopeful the country's status on the US watch list would improve as migrant labour problems are being tackled.
Thailand is on the US government's Tier 2 watch list in the Trafficking in Persons Report. The US will review the country's status this month.
Pakphum Sawaengkham, a labour activist in Samut Sakhon, said the NV extension would help solve human trafficking as illegal migrant workers passing the process would become legal workers and enjoy social welfare benefits.
However, he said some migrant workers were not paid their wages and so they had no money to pay for the NV process.
Many migrant workers have fallen prey to human trafficking gangs and this pushed the country onto the Tier 2 watch list.
Mr Prawit said the department has opened 12 verification centres across the country to facilitate the NV process. They are in Samut Prakan, Samut Sakhon, Surat Thani, Songkhla, Pathum Thani, Rayong, Kanchanaburi, Khon Kaen, Chiang Mai, Chiang Rai, Tak and Ranong.
He urged employers hiring illegal migrant workers to submit lists of their migrant workers, employment contracts and employers' letters to the department by March 16.
After the documents are filed, the migrants will be issued temporary passports before undergoing the NV process, he said.
There were concerns from some labour advocates that the 120-day extension period may not be enough.
Mr Prawit spoke during a seminar on migrant workers' employment registration in Bangkok yesterday.
The seminar was jointly held by the department, the International Labour Organisation, the International Organisation of Migration and the Migrant Working Group.
Aemasho, an activist and representative for Myanmar workers, said labour exploitation was a serious issue.
Adisorn Kerdmongkol, a senior policy adviser to Thailand-based International International Rescue Committee which assists migrants and cross-border refugees, said the 120-day extension period would not be enough for the NV process as the number of unregistered migrant workers exceeded 1 million people.