Troop build-ups on both sides of the Thai-Cambodian border have heightened fears of clashes following Thailand's withdrawal from Unesco's World Heritage Convention.
Army chief Prayuth Chan-ocha said he had ordered troops stationed along the border to be prepared as the chance of clashes was high.
His comments came after the Second Army reported Cambodia was bringing in more troops to the border yesterday.
Gen Prayuth said he had decided to boost Thailand's troops and reinforce bunkers as a precaution. The moves were purely defensive and not intended to indicate military aggression.
The army chief stressed troops were duty-bound to protect the country's sovereignty.
''If Thailand's sovereignty is violated, soldiers can use their weapons straight away,'' Gen Prayuth said.
The army chief said Prime Minister Abhisit Vejjajiva had also ordered the army to be on full alert along the maritime border with Cambodia off Chanthaburi and Trat.
Gen Prayuth said Thai and Cambodian soldiers have been in contact on a regular basis since the last border clashes.
''Admittedly there is some distrust between the two sides. Troops from both sides are positioned close to each other. Chances of military clashes are high,'' Gen Prayuth said.
Following Thailand's withdrawal, it was necessary for the senior military leaders of the two countries to discuss what steps should be taken to avoid a military conflict, he said.
''Don't be frightened, because I believe no one wants to fight and that holding talks is the solution to the problem,'' Gen Prayuth said.
The army chief yesterday met Natural Resources and Environment Minister Suwit Khunkitti by chance at Suvarnabhumi airport and praised him for making the right decision to withdraw Thailand's membership of the World Heritage Convention.
Gen Prayuth was leaving for South Korea just as Mr Suwit was returning from Paris.
The decision to withdraw was made by Mr Suwit, who led the Thai delegation to the World Heritage Committee meeting in Paris on Saturday.
Army spokesman Sansern Kaewkamnerd yesterday said Thai military representatives had met for talks with their Cambodian counterparts.
Thai soldiers proposed that the two sides pull their troops away from the disputed border area near Preah Vihear temple to ease tensions.
But the Cambodians rejected the proposal and troops on both sides remained on alert, Col Sansern said.
Col Prawit Hukaew, spokesman for the 2nd Army, yesterday said Cambodia had brought in more troops, more weapons and reinforced their military bases along the border.
Col Prawit said the 2nd Army was closely monitoring the movements of Cambodian soldiers and was ready to respond if the Cambodian military started anything.
He said the 2nd Army believed Mr Suwit's decision to withdraw from the WHC was intended to protect the national interest and the country's sovereignty.
Col Prawit said relations between Thai and Cambodian soldiers in the border areas remained healthy. Unit commanders in the area have been in regular contact.
However, Col Prawit said that any decision by Cambodian Prime Minister Hun Sen will be a decisive factor in the border situation.
Prime Minister Abhisit yesterday said the cabinet would today discuss the legal implications of Thailand's decision to withdraw from the World Heritage Convention.
Mr Abhisit said government agencies would be instructed to study and report on the legal implications for Thailand and steps which needed to be taken by the next government after Sunday's election.
He also said the withdrawal would have no effect on negotiations to resolve border disputes between Thailand and Cambodia.
Thailand would still adhere to the memorandum of understanding signed in 2000 in further negotiations with Cambodia, Mr Abhisit said.
Dialogue is a main mechanism to address border conflicts and must proceed, Mr Abhisit said, adding that Thai land had the right to reapply for membership at a later date.
The People's Alliance for Democracy, meanwhile, has said it will call off its anti-government demonstration planned for Friday.
''We have now won our demand for Thailand's withdrawal from the World Heritage Convention, although we have yet to achieve our ultimate goal in clearing all Cambodian people from Thai territory,'' spokesman Parnthep Pourpongpan said.
He urged the government to formally inform the International Court of Justice that Thailand will not accept its ruling concerning Cambodia's call for it to interpret its previous verdict on the Preah Vihear temple.
''Without doing so, the government may not be able to protect the country's territory,'' he said.
Unesco director-general Irina Bokova has expressed regret over Thailand's decision to withdraw from the World Heritage Convention.
She hoped Thailand would reconsider its decision.
Meanwhile, tensions were also rising near Ta Kwai temple in Surin's Phanom Dong Rak district following Thailand's withdrawal.
A military source said on the Cambodian side at least 300 Cambodian soldiers had built bunkers and artillery guns were deployed opposite Ban Thai Niyom Pattana on the Thai side.