HAT YAI, Aug 10 — A secondary school in southern Thailand with about 3,600 students has been forced to close for two days after a sacked foreign teacher allegedly posted gun-related images and threatening messages aimed at the school community.

Hatyaiwittayalai School in Songkhla province will keep its gates shut on Monday and Tuesday, with lessons moving online as a precaution, the Bangkok Post reported.

School director Thitiwit Meechooworapong announced the closure on Saturday night, saying it was intended to protect students, teachers and other employees.

The decision followed alleged threats by Pieter Johannes Dreyer, a former English-language teacher in the school’s English programme.

Police said Dreyer, a South African national, had already left Thailand. He departed through the Padang Besar border checkpoint in Sadao district on July 19 and had not returned, according to the Bangkok Post.

The school said his employment was terminated on July 24 for breach of contract.

Dreyer subsequently allegedly posted threatening material in a school LINE chat group with about 5,000 users, including photographs of himself firing a gun, images of school executives, messages and an audio clip.

He was also said to have criticised the school’s management.

Thitiwit said school administrators considered the material a threat to students, teachers and management and had filed a complaint with Hat Yai police.

Immigration authorities said Dreyer had since been blacklisted.

Police said Dreyer left Thailand on July 19, while the school said his employment was formally terminated five days later on July 24.

Hatyaiwittayalai, on Phetkasem Road in Hat Yai district, has about 250 teachers and staff in addition to its roughly 3,600 students.