Thai authorities have charged eight Muslims with treason, saying they were key figures in a campaign of violence in the country's south.
Violence continues to flare up in the country's south
More than 600 people have been killed in clashes in Thailand's largely Muslim south since January last year.
The men, who officials say belong to an outlawed separatist group, face death by lethal injection if found guilty.
All eight defendants, who work as teachers in Islamic schools, deny the charges against them.
The teachers stand accused of training young men to kill civilians, attack troops and set fire to schools and government buildings.
Home to most of Thailand's 4% Muslim minority
Muslim rebels fought the government up to the mid-80s
Suspected militants have upped attacks this year, targeting Buddhists
Security forces' response criticised by rights groups
Thai Prime Minister Thaksin Shinawatra has described the men as significant ringleaders in the insurgency.
"They have ambushed officials, killed monks, teachers and students, set fire to schools and other government buildings, and stolen weapons," the prosecution said in a statement, according to Reuters.
The unrest in the Thai south shows no sign of abating.
Small-scale attacks take place on a near-daily basis in the three Muslim-dominated provinces of Yala, Pattani and Songkhla.
The government has been criticised for its heavy-handed tactics towards the insurgents.