More than 4,000 workers, mostly foreign labour, on Wednesday staged a protest at a pineapple factory in Kanchanaburi province, demanding the government's promised 300 baht daily minimum wage.
Reports said most of the workers are from neighbouring Myanmar.
Police arrived at the factory to deal with the protesters.
The government's 300 baht daily minimum wage policy took effect in April 1. The raise is 40 per cent from current levels.