At least 300 police officers will be guarding Government House when anti-government demonstrators rally at nearby Democracy Monument in Bangkok on Sunday.
Prateep Keeratireka, deputy secretary-general to Prime Minister Prayut Chan-o-cha, on Friday invited officials from security agencies to discuss their plans, even though the protesters had not formally announced any intention of marching to the site.
The protesters have called another major rally at Democracy Monument, on Ratchadamnoen Avenue, saying only they planned to march to "an undisclosed location". They will reiterate their long-held demands: Gen Prayut's resignation, the rewriting of the constitution and reform of the monarchy.
The agencies at the discussions included the National Security Council, the Royal Thai Police's Special Branch, the Metropolitan Police Bureau (MPB) and the National Intelligence Agency.
Pol Col Watcharawee Thamsema, commander of the Special Branch Division 3, said later that a combined force of 300 officers from the Special Branch and MPB would be on duty at Government House.
However, Gen Prayut, who also serves as defence minister, had not issued any special instructions for handling the protesters, he said.
Pol Col Watcharawee added that the meeting had discussed the possible routes that the protesters would take and measures for dealing with them.
Deputy Prime Minister Prawit Wongsuwon, who is also the minister in charge of national security, warned the protesters not to break the law, even though he admitted that intelligence agencies had so far found nothing amiss.
Interior Minister Anupong Paojinda said he had instructed officials to maintain order in other provinces where protesters may also plan similar rallies.
In another development, a group of high school student activists calling itself "Bad Students" said on Friday that they had scheduled a rally for Nov 21, at which they would demand Gen Prayut to take responsibility for appointing Nataphol Teepsuwan as education minister and resign.
The group has also demanded Mr Nataphol's resignation, claiming he has failed to improve the quality of education or allow more freedom at schools.
"Since our calls for Education Minister Nataphol Teepsuwan to change the system and quit didn't work, we feel it necessary to up the ante by targeting the higher authority of Prime Minister Prayut Chan-o-cha instead," group leader Laponpat Wangpaisi told reporters at Democracy Monument.
The group has not revealed the time and place of the Nov 21 protest but said they would be raising political issues on top of calls for education reform.
"It's clear that politics is the core problem of everything in this country," Mr Laponpat said.
"I cannot say yet if our demands will be exactly the same as other pro-democracy groups but I can tell you that we want the PM to get out."
Last month, the Bad Students group toured five well-known high schools in Bangkok on a convoy of trucks to condemn Mr Nataphol for failing to defend the students' right to protest.
They said there had been more than 100 cases of students being intimidated by schools and teachers for taking part.
They also submitted three demands to the Education Ministry: stop harassing students, scrap outdated regulations and reform the educational system.
They further called for the minister to quit if he could not help them.
Mr Nataphol said he was ready to listen to students' demands.
However, he said his ministry had already taken action by proposing several policies to address their concerns.
