Smoke pours out of a two-storey building at Prang Ku School in Si Sa Ket, where a fire broke out yesterday morning. The damage was estimated to total at least Bt1 million.

A fire at a secondary school in Si Sa Ket yesterday morning caused damage totalling at least Bt1 million and disrupted students' mid-term exams.

The Prang Ku School, which has 1,888 students, is a famous institution in the north-eastern province. It is located just 500 metres from the Prang Ku police station.

At press time yesterday evening, police were gathering evidence in a bid to determine the cause of the blaze. Arson was a possible cause, they said.

"We are in the process of investigating and gathering evidence," Provincial Police Region III commander Lt-General Sathaporn Laothong said yesterday.

Sathaporn said police in his area had been working closely with kamnans, village heads and volunteers to keep a watch on schools.

Since the September 19 coup, about 20 schools have been set on fire in the North and Northeast provinces, where political support for ousted premier Thaksin Shinawatra is high. Police suspect many were arson attacks.

The Provincial Police Region III covers Nakhon Ratchasima, Chaiyaphum, Buri Ram, Surin, Si Sa Ket, Ubon Ratchathani, Amnat Charoen and Yasothon.

Sathaporn yesterday called on school administrators, teachers and janitors to help keep watch on their schools because police could be stationed at critical areas only.

He said investigators had found that the Prasarn Witthaya School fire on Sunday was caused by the reckless actions by two workers - Nong Payakdej and Amunuay Tib-ngern. The two were welding an iron structure at the school when a spark set a plastic partition alight.

"They are charged with recklessness that led to a fire," Sathaporn said, noting that the suspects confessed and there were witnesses to support the charges.

Meanwhile, an investigation into the December 16 fire at Ban Sakadnak Wittaya School was progressing well, Sathaporn said. It showed the fire appeared to have been deliberately lit.

A cash reward of Bt300,000 is being offered to anyone with useful information that can lead to the arrest of any arsonists for setting schools alight.

"Relevant officers will meet on Friday before concluding the investigation and identifying suspects," he said.

Also yesterday, National Police Deputy Commissioner Lt Gen Patcharawat Wongsuwan summoned commanders to provincial regions which have had school fires - except those from the South - to clarify the situation and step up security measures for schools.