The Barisan Revolusi Nasional (BRN) guerrillas were responsible for Tuesday's car bomb in Songkhla's Thepa district, according to Deputy Prime Minister Prawit Wongsuwon, as three suspects were detained yesterday.
The authorities were closely monitoring BRN activities and working to prevent further attempts to stir up unrest, said Gen Prawit who is also in charge of national security.
He said 4th army commander Pornsak Poonsawat has sent teams to tighten security in areas in the far South prone to attacks.
Gen Prawit noted the BRN has not joined the Malaysia-brokered peace talks with the Thai government. In the meantime, the deputy premier said the government will continue talks with Mara Patani, an umbrella group comprising representatives of five liberation groups, including the National Revolutionary Front, Patani Islamic Liberation Front, Patani Islamic Mujahideen Movement and two Patani United Liberation Organisation factions -- Pulo-DSPP and Pulo-MKP.
On Wednesday, the National Human Rights Commission issued a statement condemning the car bomb and urged the authorities to bring the attackers to justice as soon as possible.
On Tuesday, authorities said the insurgents responsible for the bombing were led by Bukori Lamsoh and Seri Waemanu.
The explosion occurred at dawn on Tuesday along a local road in tambon Tha Muang, destroying a power transformer and injuring two policemen. The blast was heard 10km away and scattered shrapnel across a 300-metre radius.
The bomb was packed in two 15kg gas cylinders in the back of a pickup truck stolen from a retired teacher, Amata Samothanthawee, 62. Amata was hanged by the insurgents at his home in Saba Yoi district hours before the truck was used to launch the car bomb. The scene was still cordoned off yesterday as forensic police collected more evidence.
A security source said three people from Saba Yoi district were detained on Tuesday night in connection with the bomb attack.
The three denied any role in the attack, but police believe they acted as lookouts and warned the bombers when police were approaching.
They also believe there were two other teams involved; one which killed the retired teacher and took his vehicle; and another which assembled the 50-kg bomb and placed it in the vehicle.
Police also think the attackers took side roads to avoid being spotted on CCTV.