Suspected militants have shot dead two Thai soldiers and burned their bodies, police said on Friday (Jul 17), in the latest outbreak of violence in the kingdom's insurgency-battered deep south.

The drive-by shooting in the Ruso district of Narathiwat province took place shortly before noon on Thursday, the last day of the holy Muslim month of Ramadan, a period when the region often sees a surge in attacks.

"Around nine gunmen on a pick-up truck followed the victims (in their truck) and first shot dead the driver," district police chief Rueangsak Buadaeng told AFP, explaining the driver, aged 29, was one of the soldiers killed.

As the vehicle crashed into roadside food stalls, a second soldier, 22, was also shot dead, he said. Their bodies were then set alight in the truck, Rueangsak added. Police are still questioning eyewitnesses and have not made any arrests yet.

More than 6,300 people have been killed in the Thai south since 2004 in a conflict largely ignored by Thais and forgotten by the wider world.

Rebels there are seeking greater autonomy for the three Muslim-majority provinces bordering Malaysia with near-daily violence between security forces and the insurgents rocking the region.

Rueangsak said three protest banners were found in the Ruso district Thursday with one reading "colonisers are inhumane and always lie to the international community".

Buddhist-majority Thailand annexed the southern region more than 100 years ago and stands accused of perpetrating severe rights abuses as well as stifling the distinctive local culture through clumsy, and often forced, assimilation schemes.

The majority of casualties have been civilians with both Buddhists and Muslims falling victim to shadowy insurgents who target security forces, citizens and perceived representatives of state authority.

Security forces are also accused of killing civilians in raids on suspected militant hideouts and rights groups have long urged an end to a "culture of impunity" among officials.

Last Friday, four separate bomb blasts in the south left three people dead while a further four people were killed in shooting and arson attacks.

Thailand's junta, which ousted an elected government in a May 2014 coup, has vowed to reboot a stalled peace process with several rebel groups operating in the deep south but so far there has been little progress.