The Muslim-majority region borders Malaysia and has seen a decade of near-daily violence claim more than 6,500 lives.
A roadside bomb killed a 22-year-old Thai soldier today and critically wounded another member of a patrol team providing security to teachers in the country's insurgency-torn southern tip.
Police said the explosive was detonated remotely while six soldiers were doing a security sweep on a road for teachers on their way to a school in Bacho district, Narathiwat province.
"The remote control bomb went off while two of them stopped to check the suspicious object on the roadside," Viroj Boonkhae, a police officer in Bacho, told AFP.
The injured soldier has been hospitalised, he added.
The Muslim-majority region borders Malaysia and has seen a decade of near-daily violence claim more than 6,500 lives.
The insurgents seek greater autonomy from the Thai state, which annexed the region more than a century ago.
While militants mostly target state security forces, teachers and other civilians have also been the focus of bombings and shootings.
Thailand's military, which seized power in a 2014 coup, has touted the region's record drop in violence last year as the fruit of better intelligence-led operations by its troops.
It has also reached out to some representatives from the shadowy insurgent network in the hope of starting full-scale peace talks.
But critics say peace is unlikely to take hold as long as the military suppresses human rights in the region, which has been governed by emergency laws for the past decade.
In a report released last month, rights groups accused the army of torturing scores of detainees in its efforts to quash the insurgency.
The report's researchers said the situation has worsened since Thailand's 2014 coup.