Environmental and human rights groups have accused the Thai government of using excessive force against peaceful protesters outside the Chinese Consulate-General in Chiang Mai, where two protesters were injured on Monday.
Scores of protesters who gathered outside the Chinese Embassy in Bangkok today also called on both Thailand and China to take responsibility for cross-border pollution linked to Chinese-backed mining operations in Myanmar.
In a statement issued today, the NGO Coordinating Committee on Development (NGO-COD) claimed that the police operation on July 6, during which more than 100 officers dispersed demonstrators outside the Chinese Consulate, was the direct consequence of a deliberate decision to deploy state power rather than an unavoidable incident.
The group said at least two protesters suffered broken arms, arguing that the incident represented an attack on the rule of law, human rights and democratic freedoms.
It questioned why police had used force against environmental defenders while, it said, those responsible for the pollution had not been held accountable.
It called on the Thai government to immediately halt the use of force against peaceful demonstrators, establish an independent investigation into the July 6 police operation, prosecute those responsible if wrongdoing is found, and provide compensation to those injured.
The statement said the protest was held to draw attention to transboundary pollution affecting the Kok, Sai, Ruak and Mekong rivers in Chiang Mai and Chiang Rai provinces, which campaigners say is caused by Chinese-backed rare earth and gold mining operations in Myanmar's Shan State.
Protesters held placards reading, "This is Thailand, not Tiananmen," and "Stop violence against environmental defenders." Other placards read, "Clean energy should not cause dirty rivers" and "Pollution has no borders. Responsibility shouldn't either."
Some protesters were also seen wearing masks depicting Chinese President Xi Jinping.
NGO-COD said the environmental crisis has become a broader issue of cross-border accountability, corporate responsibility and state obligations under international law rather than simply an environmental dispute.
Citing findings from Thai government agencies, academics and affected communities, the group said water turbidity at the Thai-Myanmar border has reached nearly ten times normal levels, while arsenic concentrations exceed Thailand's safety standards in several rivers.
It also claimed that lead contamination has been detected in multiple communities and that more than 94 native fish species have already been affected.
The organisation warned that unless the source of the contamination is stopped, the Mekong River system could face one of the worst transboundary pollution crises in its history within the next one to two years.
The statement referred to UN Communication AL THA 1/2026, in which ten UN Special Rapporteurs and Working Groups linked pollution affecting the rivers to rare earth and gold mining operations in Shan State.
According to NGO-COD, the UN experts concluded that Myanmar, as the source of the pollution, and China, as the principal source of investment and the primary destination for the extracted rare earth minerals, both bear responsibility for the resulting environmental damage, while Thailand has an obligation to protect the rights of people within its territory.
The group also cited scientific research by Thailand Science Research and Innovation (TSRI), saying environmental DNA (eDNA) analysis established a direct link between upstream mining activities and downstream river contamination.
NGO-COD further alleged that minerals extracted from the mining operations enter China's industrial supply chains for products such as electric vehicles and wind turbines, while some are processed in Thailand before export.
The campaigners also urged the Chinese government to ensure that overseas investments under its Belt and Road Initiative comply with international environmental and human rights standards, arguing that the initiative's commitment to building a "Green Belt and Road" must be matched by accountability for cross-border environmental impacts.
"If profits can cross borders, responsibility must cross them as well," the statement concluded.
