Some 775 children under 18 had gone missing over the past three years and most disappeared during the summer break, according to a Royal Thai Police report, he said.

Eighty-two children were reported missing last year and 14 more "had disappeared" from October up to March this year, he said.

Padungsak urged parents to watch out for criminals among crowds and to tell police about any suspicious incidents. He also asked people who witness child labour abuses to call the Labour Ministry on 1506.

Padungsak cited a case of two young teenagers boys from Buri Ram on their way to look for construction jobs in Bangkok. The pair were drugged in the toilet at Mor Chit bus station. They later regained consciousness on an offshore fishing boat and were told they had been sold for Bt10,000 each and had to work without payment for seven months, he said.

After, the department helped by getting the Social Development and Human Security Ministry to give them some money - Bt1,900 each. The pair returned to Buri Ram, where the labour office gave them vocational training.

Padungsak also pointed out that the Labour Protection Act 1998 stipulates that employers cannot use workers under 15, while the employment of youths under 18 must be reported to labour officials within 15 days of hiring.

Employers must also provide at least an hour's break after four consecutive hours of work to employees under 18. And they can only work between 10pm to 6am if their employers obtain legal permission. They were not allowed to work overtime, or work in dangerous conditions or at inappropriate venues, he said.

People who violate the law would face up to one year in jail or/and a fine up to Bt200,000.