Thailand's army said on Sunday that 10 Muslim activists remained in custody out of a group of 22 detained in the south on April 2 under martial law in connection with a car bombing.
Thailand is predominantly Buddhist but parts of the south are majority Muslim. A low-level insurgency in the region has claimed more than 6,000 lives since January 2004 when resistance to Buddhist rule resurfaced violently.
The army detained the activists in raids on student dormitories in the southern province of Narathiwat on Thursday.
The raids drew the criticism of Human Rights Watch, which demanded an end to arbitrary detentions and the group's immediate release unless charged with a credible offence.
Four of those detained have confessed to having some connection to a car bombing on Feb. 20, Thai army Internal Security Operations Command spokesman Pramote Prommin said by telephone on Sunday. Local media reported that 13 people were injured by the blast.
The army has released 12 of those detained, and expects to release four more on Sunday, Pramote said.
The detainees have been kept at three different military camps, he said, and defended the army's use of martial law to hold the activists.
"This is about using the law to search and arrest perpetrators of a crime," he said. He said the detained were former students.
Thai student protesters bore the brunt of the toughest response of the ruling junta to dissent since the days after a coup in May 2014 that ushered in army rule.
The junta on Wednesday lifted martial law across most of the country, some 10 months after imposing it just before the coup. The military retains sweeping powers under a clause in the interim constitution.
Narathiwat and neighbouring provinces Pattani and Yala have been under martial law since 2004, when a decades-old resistance movement resurfaced.
The government of coup leader and Prime Minister Prayuth Chan-ocha vowed to make peace in the south a national priority but has made little progress. Successive governments have tried to quell the insurgency without success.
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