Prime Minister Prayut Chan-o-cha on Thursday declared that "all laws and all articles" will be enforced against protesters who break the law. Gen Prayut gave his warning in a statement issued from his office, in the face of street rallies by pro-democracy protesters demanding his removal, as well as reform of the monarchy.
He said the government and various agencies had tried to find a peaceful way out of the conflict, following legal procedures.
However, the situation has showed no sign of easing, despite the government showing its sincerity about solving the problems, the premier said, adding that security agencies had done their job in maintaining peace and order and dealing with protests with the utmost care, in line with international standards.
"The situation is not easing in a good direction and there is a tendency for conflict to escalate into more violence. If not addressed, this could cause damage to the country and the beloved institution, as well as to peace and the safety of people's lives and property," Gen Prayut said in the statement, which was in Thai.
"It is necessary for the government and security agencies to intensify their actions by enforcing all laws and all articles to take action against demonstrators who break the law and show no respect for the rights of other people.
"Action will be taken in line with the country's judicial process and international standards," he said.
The statement did not specify whether this action would include the use of Section 112 of the Criminal Code, the lese majeste law, which forbids insulting the monarchy and comes with a hefty prison sentence. Gen Prayuth said earlier this year the law was not being used, at the behest of His Majesty the King.
Many thousands of pro-democracy protesters descended on Ratchaprasong intersection during their huge rally on Wednesday night, again announcing their demands for the prime minister's resignation, charter amendment and reform of the royal institution.
Expletives were painted on walls and on roads during the rallies. The People's Movement protesters announced the next rally will be on Nov 25.
Even though the prime minister did not specifically refer to Section 112, Move Forward Party MP Rangsiman Rome on Thursday tweeted that the prime minister's announcement was not a wise decision and would worsen the situation.
"Enforcement of Section 112 is tantamount to dragging the monarchy into the conflict," Mr Rangsiman said.
Responding to the statement, protest leader Arnon Nampa took to Facebook, saying the protest movement will stick to "a peaceful method". "We are ready to step up the fight in a peaceful manner," he said without elaborating.
The two major opposition parties, Pheu Thai and Move Forward, denounced the prime minister's decision to intensify the government's response to protest violence, saying it would not solve any problems.
Pheu Thai spokeswoman Arunee Kasayanont said that at a time of extreme political conflict, heavy law enforcement might not be the right solution but the government should allow stakeholders to take part in solving national problems.
Ms Arunee said the prime minister's announcement did not specify clearly which laws would be enforced against protesters, and this ambiguity could worry demonstrators and may only trigger more violence.
Nattacha Boonchaiinsawat, spokesman of the Move Forward Party, said the prime minister's statement was an excuse to exercise sweeping powers, while the protest movement's actions, although escalating, remained symbolic.
Shops remained open and electric trains continued to run despite the rallies, because operators know the demonstrators are not rioters, he said.
Pol Maj Gen Piya Tawichai, deputy chief of the Metropolitan Police Bureau, said on Thursday police would be prepared to use the lese majeste law against protesters if he receives such an instruction.