The infiltration is in an advanced stage as the militants can mobilise mass support and direct their supporters, who now include women, to fight the authorities, Ongkorn said. He told reporters he had ordered intelligence agents  to analyse the infiltration to uncover the factors driving it.

Militants are now very active, and violence in the predominantly Muslim region has been reignited after a brief cooling off over the past months, Ongkorn said. Local residents and security officials are being killed daily in drive-by shootings and bombings, he said.

Women are playing a bigger role in the attacks, he added. It was mainly female villagers who took two teachers hostage and brutalised them at Narathiwat's Ban Kuching Reupah School. One of the two teachers, Juling Pangamoon, was beaten into a coma, and doctors said yesterday her condition had not improved.

Police have arrested a dozen suspects, mostly women, for alleged involvement in the crime and have issued 25 arrest warrants.

Ongkorn said he had instructed public-relations units to launch a psychological campaign to win over residents of the militant-infiltrated villages.

Wicharn Atikaphan, president of Southern Border Teachers' Federation, said teachers in the region were worried that there could be more incidents like the one at Ban Kuching Reupah School and have agreed to accept more troops in their villages.

The federation has set up a network to ensure quick communication with district authorities and the military as a preventive measure, Wicharn said.

"We welcome a plan to boost the number of troops in the region by October," he said.

Meanwhile, the future of about 200 pupils at Kuching Reupah School remains unclear as the school was closed after the hostage-taking incident.

A school nearby in Ban Ba Ngo in Rangae district has refused to take the pupils as local residents and teachers fear reprisals from militants, said the dictrict's chief educator, Pol Sriwang.