The two fires were initially believed to be the work of southern insurgents as security authorities found hundreds of caltrops scattered on the roads to the two places to stop and impede vehicles.
At the fire inside the construction site of Shinavorn Construction Co in Muang district, seven vehicles which included a tractor, a backhoe and pickup trucks were burnt.
Meanwhile at almost the same time in Bannang Star district, fire also broke out at a para wood factory.
After being alerted of the fire, water trucks and rescue team immediately rushed to the scene but they were impeded by caltrops scattered along the way on Highway 410 to the factory.
Security authorities believed the arson attacks were meant to create unrest as a team of representatives from the Organisation of lslamic Cooperation (OIC) was scheduled to visit the deep South today.
The planned visit was called off by the Internal Security Operations Command for security reason.