The Burapha and Suranaree task forces had checked movements across the border for the past three months, acting on orders from army chief Gen Prayuth Chan-ocha, and found no evidence to support the claim, Isoc spokesman Col Banpot Poonpien said.
He did not deny that armed foreigners could sneak into the country in many areas because of the long porous nature of the border. The Burapha task force mans security areas on the border with Cambodia in eastern provinces, and the Suranaree Task Force is responsible for the northeastern border.
Protest leader Suthep Thaugsuban of the People's Democratic Reform Committee has alleged that a special force from Cambodia had been brought in to attack demonstrators.
Cambodian Foreign Ministry spokesman Koy Kuong dismissed the claims on Tuesday and said the Cambodians were in Thailand for work and business.
A member of the Thai navy top brass, Rear Admiral Winai Klom-in, alleged on Jan 21 that Cambodians have been smuggled into Thailand to carry out violent attacks on anti-government protesters - similar, he said, to what happened prior to the red-shirt turmoil in Bangkok mid-2010.
Rear Admiral Winai, commander of the Navy’s Naval Special Warfare Command, was reported as saying 10 vans carrying Cambodians entered Thailand through the eastern border that Monday night.
There were also unconfirmed media reports that Cambodian-speaking men with no IDs had been blocked by protesters from entering the Wat Sri-iam polling station in Bang Na area on Jan 26, before the fatal shooting of Sutin Tharatin.