About 20 activists of the "Stop Fracking Thailand" group rallied at the United States embassy in Bangkok on Monday morning in protest against the use of fracking by US companies drilling for natural gas in Thailand, complaining that it was polluting the environment and food chain.
The people condemned the use of fracking, or hydraulic fracturing, technology they said several American companies were using to extract natural gas from drilling concessions on land and undersea in Thailand.
Hydraulic fracturing involves the high-pressure injection of fluid - usually water, sand and chemicals - when drilling, to fracture shale rocks so that they release natural gas.
The complainants said the technology contaminated the environment, water and food chains at the production point in many areas, including Ban Namun in Doon Sat sub-district of Kranuan district in Khon Kaen.
In their letter, the group asked the US congress to investigate the process of fracking and called for a halt to its use in Thailand.
The US embassy allowed Smith Tungkasmit, an environmental engineering lecturer at Rangsit University, and Paipat Samanchuen, who represented the group, to submit their letter. The rally then dispersed.