Witnesses said the fire at Chumchon Na Pho School in Tambon Na Pho started on a staircase at about 00.30am yesterday and quickly burnt down the building.

The damage was estimated to be worth more than Bt1 million, with the building alone costing Bt775,000.

The school had 375 students from kindergarten to Mathayom 3 level and employed 24 teachers.

Police suspect either a short-circuit or an arson attack. The interrogation of six people - including the school's director, teachers and janitor - did not reveal any conflicts that could have been a motive, said Na Pho police superintendent Colonel Tawan Thiampolkrang.

However, Second Army Region commander Lt-General Sujet Watanasuk, who inspected the school later yesterday, said it was most likely an arson attack as the Education Ministry had had vocational students install new wiring and safety circuit-breakers two months ago. However, the Army will wait for the results of the police investigation into the cause of the fire.

Yesterday's school blaze was the fourth in the north-eastern province since the September 19 military coup. The first was at a school in Non Din Daeng district in September, the second at a school in Chalermprakiart district in November and the third at a school in Satuk district last December.

The acting director of Educational Service Area 4, Sa-nga Chanwiset, said he had reported the fire to the Education Ministry and set up a fact-finding committee to investigate.

A source said an on-duty teacher was not at the scene when the fire started and a security guard hired by the school for Bt100 per day, Somporn Khanenok, was cooking at his home at the time.

Meanwhile, secretary-general of the Office of Basic Education Commission Khunying Kasama Varavarn said she had already asked the Local Administration Department to assist the school.