Eight soldiers were killed and six wounded in ambushes by suspected separatist militants in Thailand's rebellious Muslim south on Monday, army and police spokesmen said.

"The soldiers were ambushed after escorting teachers to schools and eight of them were killed," army Colonel Acra Tiproch said.

The ambush occurred near a village in Narathiwat province. A military Humvee was blown up by a 20-kg (44-lb) roadside bomb, then at least 20 militants attacked, police said.

"The head of one of the dead soldiers was found next to the upside-down Humvee and the faces and bodies of others were hit with so much shrapnel and bullets that they can't be recognised," a local journalist who visited the scene said.

The militants walked away with eight M-16 rifles and an M-60 machinegun, an army statement said.

Bomb squads defused a second roadside bomb meant to hit officials rushing to the scene, police said.

Another group of soldiers escorting teachers, themselves frequent targets in four years of separatist insurgency as a symbol of the largely Buddhist state, also clashed with militants and two were wounded, he said.

Suspected militants also disrupted the mobile phone network in the three southernmost provinces, where 2,800 people have been killed in the latest insurgency in the former sultanate populated largely by ethnic Malays.

Acra said rebels had set several transmission towers on fire.

Despite an army "hearts and minds" campaign, 2007 was the bloodiest in the region since the insurgency began four years ago, a Thai research institute said last week.

Nearly 800 people were killed last year, taking the death toll to 2,776, according to the Deep South Watch think tank at Pattani's Prince of Songkhla University.