The army has dismissed media reports about tensions over a standoff between Thai military forces and United Wa State Army (UWSA) fighters in Mae Hong Son's Pai district.
Army spokesman Col Thirat Sombatsiri on Wednesday rejected the claims, which emerged on social media.
"The overall border situation was normal, and there is no confirmation about any violence along the border as reported by the media," he said.
He said the army has ordered the Third Army Region to offer more details about the actual border situation in Pai.
Col Rungkhun Mahapanyawong, spokesman for the Third Army Region, said the border situation in Chiang Mai and Mae Hong Son was normal, and people in the border areas were going about their lives.
The spokesman said the relationship between the Thai regional army and the UWSA in these areas was also normal.
"Even the border situation in the areas adjacent to land the UWSA currently occupies is normal. Both sides still maintain a good relationship," he said.
He said the army will work to the best of its ability to protect the country's sovereignty.
However, a source said the Ministry of Defence instructed the army to prepare forces and munitions to protect Thailand's sovereignty in the northern border areas, particularly in Mae Hong Son.
The orders came while the border situation was tense, with UWSA reinforcements observed at its main border bases, Doi Hua Ma and Nong Luang, and five other outposts, which are situated in Pai, the source said. The Thai army now wants the UWSA to retreat, but the latter doesn't agree, said the source.
The Thai army now expects an answer from the UWSA to its request for it to leave these areas by Dec 18. The request was made during talks between six high-level UWSA members and Thai authorities held in Chiang Mai on Nov 18-19.
Another source, however, cited a report by Radio Free Asia (RFA) that quoted the UWSA as saying that it could not agree with the request to back down from these areas that it strongly believes belong to it.
Assoc Prof Dulyapak Preecharush, from Thammasat University, suggested the government try to engage China and other nations in the Mekong River Basin, also affected by transborder drug trafficking problems, in new negotiations.
He suggested these be conducted directly with the UWSA, not the Myanmar army.