Hundreds of high school students in Bangkok have protested in the latest of more than a month of anti-authority demonstrations seeking reform of an education system they believe is obsolete.

Protests that started on Thai university campuses have been taking place almost daily since mid-July in a growing challenge to the Southeast Asian country's government, with some protesters seeking a reform to the strong monarchy too.

On Saturday more than 600 students gathered outside the Ministry of Education in Bangkok.

They called for the freedom to be able to speak their minds at school and the relaxation of rigid rules on uniforms and behaviour.

"Thai education has made us puppets," 18-year-old Supicha "Menu" Chailom said. "We are not robots of the system, we are the youth and have the right to express ourselves."

Last month, protests spread to some high schools, with students raising three-finger greetings at morning assemblies during the "Hunger Games," a symbol of the pro-democracy movement.

Minister of Education Nataphol Teepsuwan told reporters he respects the rights of the students.

"The problems posed by the youth are things on which we can come to understand as long as we value one another and the law," he said.

Prime Minister Prayuth Chan-ocha, the key focus of the protests, told protesters last week that they were causing tensions that could cause Thailand to crumble and leave it "wracked in flames."

He has particularly condemned those who have demanded reforms to the monarchy - once a taboo subject.

On Saturday, Thailand’s government released a cartoon drawn by King Maha Vajiralongkorn, who spends most of his time in Europe, that portrayed a happy Thai family living a contended rural life.

Several activists been arrested and charged in recent weeks for their anti-government protests.

SOURCE: Reuters news agency