Four killed in attacks in Thailand

Four people were killed in a late-night attack by suspected Muslim insurgents on a military outpost in Thailand's violence-wracked south, authorities said Wednesday.

Two soldiers and two armed civilian volunteers were killed in the bombing and shooting attack at a checkpoint in Pattani province late on Tuesday, security force spokesman said.

The attack comes as anger snowballs over the case of a Muslim rebel suspect who was left in a critical condition after spending several hours in a notorious army interrogation unit.

Security force spokesman rejected any link between the attack and the questioning of Abdullah Isamusa, 32, who was taken to an army camp from his home on Saturday and found unconscious with fluid on the brain a day later. Isamusa remains in hospital.

It was the deadliest attack in the largely ethnic Malay region since January. As with most such attacks, there was no claim of responsibility.

Anger in the south has surged over allegations that Isamusa was abused and left with brain injuries. An umbrella rebel group and civil society groups condemned the interrogation while many in the region voiced fury on social media.

The 15-year conflict in the Malay-Muslim majority 'Deep South' has left over 7,000 people dead, but garners little global attention.

Rebels seeking autonomy for the culturally distinct 'Deep South' have been fighting the Buddhist-majority Thai state, which colonised the area over a century ago.

Late on Tuesday militants struck the remote base in Pattani province, throwing grenades and laying down nearly an hour of automatic fire, an army spokesman told AFP.

The rebels stole five machine guns, burnt tyres and scattered spikes on the road as they fled to hamper any chase, he added.

Confirming the death toll, a Pattani police officer said two other people were in hospital in a critical condition, in one of the deadliest single incidents to hit the region in months.

An army statement said the camp doctor recorded the suspect arriving in good health, but said he was later found unconscious after being held in the "interrogation centre".

Inkayuth is the Thai army's biggest detention centre in the south, where rebel suspects are taken for questioning and held under the emergency laws governing the conflict-scarred region.

The army has vowed to punish anyone found guilty of abuse.

But critics say impunity reigns in the security straitjacket of the south -- no military personnel have ever been successfully prosecuted for abuses over the conflict.

Sunai Phasuk of Human Rights Watch speculated Tuesday's attack "was in retaliation" for the treatment of Abdulloh.