15 killed in suspected rebel attacks in Thailand's south

At least fifteen people were gunned down in an ambush by suspected Muslim militants in Thailand's violence-wracked south, an army spokesman said on Wednesday, one of the bloodiest days in the 15-year insurgency.

Thailand's three southernmost provinces have been in the grip of a conflict that has killed more than 7,000 people, as Malay-Muslim militants fight for more autonomy from the Thai state.

Despite the high death toll, the highly localised unrest garners few international headlines.

The region is heavily controlled by the police and the military, with residents and rights groups accusing them of heavy-handed tactics.

Villagers trained and armed by security forces are also enlisted to monitor remote villages, though they are rarely targeted by the rebels.

This changed late Tuesday when militants struck two checkpoints in Yala province manned by civilian defence volunteers, opening fire on them as a group of villagers stopped to talk, southern army spokesman Pramote Prom-in told AFP.

In the largest death toll in years, "twelve were killed at the scene, two more (died) at the hospital, and one died this morning", said Pramote, adding that five others were injured.

The attackers took M-16 rifles and shotguns from the checkpoints, he said. "These acts were by militants." Nails were also scattered on the roads in an apparent effort to slow the security forces, the army said in a separate statement.

A bomb squad was dispatched Wednesday morning to investigate and detonate an explosive device suspected to have been left by fleeing attackers about three kilometres (1.9 miles) from one checkpoint.

The southern army commander told reporters that the attackers were targeting "weak points".

"This is just to gain the headlines and scare Thai people nationwide," said Pornsak Poonsawasdi.

Prime Minister Prayut Chan-O-Cha said the perpetrators must "be brought to justice", according to Defence Ministry spokesman Kongcheep Tantravanich.

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

The conflict is characterised by tit-for-tat attacks that usually target symbols of the Thai state and its security forces but civilians from both Muslim and Buddhist communities often get caught in the crossfire.

The violence has bled into tourist destinations, like in 2012 when a series of car bombs in Songkhla province's Hat Yai killed 13 people.

The incidents have been fewer in recent years, but the hits have become "more intense", said Don Pathan, an expert on the so-called Deep South.

Tuesday's attack marked the largest coordinated effort "in a very long time", he added.

It comes days after Bangkok hosted the Association of Southeast Asian Nations (ASEAN) summit, which brought head of states from all over the world -- along with hundreds of foreign journalists.

"It (the attack) is a reminder that they are still here," Pathan said.

Civilian defence volunteers rarely draw the rebels' ire "unless if they cross the line and become part of the government security apparatus", he added.

The rebels accuse the state of railroading their distinct culture as well as carrying out routine abuses which go unpunished.

The latest incident stoking outrage in the region was the death in August of Abdulloh Esormusor, a Muslim man who was detained by the military and left in a coma after being interrogated at a notorious Thai detention centre.

Suspects are routinely taken for interrogation and held under emergency laws in detention centres where rights groups have documented torture.

Days after Abdulloh's detention, four people were killed in a late-night attack on a military outpost, fuelling speculation of a retaliatory operation.

A week later, several small bombs exploded in Bangkok, injuring four people as the city hosted a major summit attended by top diplomats, including US Secretary of State Mike Pompeo.

Thailand has linked the bombs to southern insurgents -- though no group ever claimed responsibility for the attacks.