The attack came just two weeks after 12 soldiers were killed in a similar attack as the government struggles to keep a lid on separatist violence that has left more than 2,200 people dead in three years.

Bombings, shootings and arson attacks have become daily events in the three Muslim-majority provinces in Thailand's south, and the latest bloodshed followed another night of deadly unrest across the region.

Soldiers were travelling to a school in Yala province to provide security for teachers and students when a roadside bomb exploded near their vehicle, police said. The rebels then shot the troops dead at point-blank range.

"Seven soldiers were killed and one injured. They were the security team for local teachers," said local police commander Colonel Aniruth Im-arb.

The victims had to be airlifted to hospital because the rebels had blocked the road with trees and spikes, police said.

Soldiers have been pressed into duty to try to protect students and teachers, regular targets of the insurgents -- who see them as trying to impose Buddhist Thai values on the Muslim and ethnic Malay region.

But they have ended up targeted themselves, while the violence against students and teachers has continued. Five teachers were shot dead in the region this week, while at least 14 schools were torched.

Meanwhile more than 260 schools in the region closed down this week due to security fears. Two of the teachers shot this week were women gunned down inside an elementary school library in front of their horrified students.

"Militants see teachers as important figures in the south because they can influence the minds of children. Militants are not happy with teachers," said Srawut Aree of the Muslim Studies Centre at Chulalongkorn University.

"Teachers are easy, soft targets for militants," he said.

Human Rights Watch denounced the attacks on schools and urged the government to do more to ensure the security of children.

"Insurgents are attempting to close down all government schools," Brad Adams, Asia director at the US-based rights group, said in a statement.

"Their campaign of terror strikes a serious blow to public education in the southern border provinces, which already retain the lowest test scores in Thailand," he said.

Three local Muslim government leaders were also killed overnight in an attack on their car. One suspected militant died when he accidentally detonated a five-kilo (11-pound) bomb that he was planting on a roadside, police said.

Thailand's three southern-most provinces were once an autonomous sultanate, until the Muslim-majority region was annexed by mainly Buddhist Thailand a century ago.

The Thai military currently deploys some 30,000 troops in the provinces in a bid to stem the ongoing violence.