BANGKOK (AFP) - A Thai soldier was killed and three others wounded on Wednesday (Nov 30) by a roadside bomb in the kingdom's far south where a Malay-Muslim insurgency has claimed thousands of lives in the past 12 years.

The four soldiers were travelling to set up a checkpoint in Yala, one of the main towns in the Muslim-majority region, when the bomb struck.

"It was buried under the road and detonated by radio control," Chinawat Vethayakorn of Yala provincial police said.

"The dead soldier was 22-years-old. One of the injured soldiers had his leg amputated," he added.

The attack comes three days after a heavily pregnant 26-year-old Buddhist woman was gunned down in nearby Pattani province.

Authorities say rebels also carried out that attack.

Conflict has ravaged Thailand's southernmost region since 2004, with Malay-Muslim rebels trying to shake off rule by Thailand, which colonised the culturally distinct area a century ago.

Bombs and assassinations are the near-daily reality for civilians in the area, which is heavily patrolled by soldiers and police.

Some 6,700 people have died, the majority civilians, caught between the rebels and Thai security forces.

Thai police on Wednesday said they had arrested three Muslim suspects aged 19, 22, 31 - all from the so-called Deep South - on suspicion of planning an attack on Bangkok.

The insurgency usually fails to grab international headlines but a spate of bomb attacks on tourist sites in August sharpened the focus on the conflict.

The people wanted for those assaults, which killed two people, all come from the Thai south, raising fears insurgents could eventually expand their highly localised campaign.

Peace discussions continue to stagger on, with Thai authorities unconvinced their rebel interlocutors have command and control over militant footsoldiers.

Meanwhile the rebels do not believe the Thai junta is ready to hand the south a substantial level of political autonomy - a key step towards an ultimate end to the violence.