"If the evidence is solid enough, we'll bring charges against those individuals. If they're linked to political parties, we'll dig deeper," he said.

Aree was speaking when representatives of local administration organisations paid him a New Year's visit. He condemned those behind the arsons, saying they had wasted taxpayers' money and caused children to suffer.

Prime Minister Surayud Chulanont said if the fires were an act of sabotage, the instigators should realise that they had hurt the schoolchildren's future.

"Things would be better if we joined hands to solve problems," he said.

Army chief-of-staff General Montri Sangkhasap said Army chief General Sonthi Boonyaratglin would go to Chiang Mai tomorrow to cultivate a better understanding among local people there.

Senior Army officers were instructed to reach out to locals in areas where risks of discord were still present.

"The Army invites not only Thai Rak Thai members for a talk, but also all others who we know are behind some movements," Montri said.

If any agitators are arrested, they should face harsh punishment, since they orchestrated arsons in areas under martial law, he said.

In Nakhon Ratchasima, police summoned former senator Somsak Wangsuphakijkoson and his wife, Jitrawan, who is now serving as mayor of Tambon Soeng Sang, to testify in a case relating to Ban Sakadnak Wittaya School, which was gutted on Saturday.

Jitrawan is planning to run for an MP under the Chat Thai Party banner against former MP Suporn Attawong of the Thai Rak Thai Party.

Somsak and Jitrawan denied any wrongdoing.