Education Minister Trinuch Thienthong has instructed state agencies to launch a probe into a school director and a teacher who allegedly cut students' hair as punishment for violating haircut rules in Phetchabun.

A video clip was shared on social media showing a teacher of a school in Bung Sam Phan district using scissors to cut more than 100 students' hair. He left them with ugly haircuts during morning assembly on Tuesday.

Ms Trinuch admitted the behaviour of the teacher was inappropriate as the ministry had already lifted hairstyle regulations in 2020 for both boys and girls.

The ministry will make a hairstyle policy for students in which they may wear their hair long or short. Schools will be given the freedom to come up with hairstyle rules suitable for their students.

However, cutting students' hair as a punishment is inappropriate and cannot be tolerated, she said.

She had told the Office of the Basic Education Commission to start a probe into the school director and teacher. The pair will face disciplinary action if their actions were proven to be incorrect, she said.

The clip was posted by Bad Student, a group that promotes the rights of students, on its Facebook page and also uploaded to its Twitter account.

Netizens condemned the actions of the teacher and called for the revocation of his licence. One netizen also urged the school to focus on teaching rather than student hairstyles.