A series of bombings in Bangkok and Nonthaburi, which injured four people on Friday, is likely to be linked to insurgents in the deep South, although political motivations have also not been ruled out, security sources said.
After security and intelligence agencies chaired by Deputy Prime Minister Gen Prawit Wongsuwon met on Friday night, sources said authorities believe the attacks to be linked to an expansion of operations by the insurgents. However, their attacks may be backed by political and other groups.
Meanwhile, national police chief Chakthip Chaijinda said an initial police investigation has found the bombings were probably carried out by the same group of insurgents who perpetrated bomb attacks in seven southern and central provinces in August 2016.
"Although it was the same group, this time they used new members who had no criminal records to carry out the attacks in Bangkok," Pol Gen Chakthip said, adding that he believed they had reconnoitred the targeted areas beforehand.
The police chief gave assurances that authorities can bring the situation under control, and said that he has appointed his deputy, Pol Gen Chaiwat Kateworachai, to lead an investigation into the blasts.
Pol Gen Chaiwat led a probe into the deadly bombing of the Erawan Shrine in August 2015.
Seven bombs were reported in five locations in Bangkok and Nonthaburi on Friday, with five of them going off, hurting four people.
The blasts included one at Chong Nonsi BTS station near the King Power Mahanakhon building, the Government Complex on Chaeng Watthana Road, and the Royal Thai Armed Forces Headquarters.
Fires also broke out at three locations in Bangkok's Pratunam area on Friday. Of the blazes, one was suspected to be arson and objects resembling bomb fragments were said to have been found in the wreckage.
Pol Lt Gen Ronnasilp Phusara, commander of Provincial Police Region 9, said that two suspects from Narathiwat's Rue So district were arrested on Thursday for planting a time bomb in front of the Royal Thai Police headquarters on Rama I Road.
An investigation found links between the two suspects and southern insurgents, Pol Lt Gen Ronnasilp said.
A police source said that the bomb was set to go off at 8am on Friday. The pair were arrested in Chumphon province.
Sources among the bomb disposal experts from the South said that the bombs at several locations in Bangkok were improvised devices triggered by timers. They were designed to cause panic rather than inflict mass casualties, the sources said.
"These bombs are similar to cluster bombs used in the serial bomb attacks in seven southern and central provinces on Aug 16, 2016," the source said.
Damage and injuries were minimal but the timing of the incidents, during a high-profile Asean meeting, suggested embarrassing the government was the main aim.
The incidents occurred on the same day that Prime Minister Prayut Chan-o-cha, now in charge of a civilian government, made his first visit to the Royal Thai Police head office, which he has pledged to oversee directly.
The sequence of attacks and the reaction by security authorities attracted extra attention from the large foreign media corps currently in the capital to cover the meeting of Asean foreign ministers. They were joined by many other senior diplomats including US Secretary of State Mike Pompeo and his Chinese counterpart Wang Yi.
Security was tightened around the Centara Grand at CentralWorld, where the Asean meetings were under way involving ministers from 31 countries in all.
Gen Prayut said he had instructed the national police chief to look after the injured people, and urged the public to join forces with authorities to keep an eye out for and take photos of suspicious persons to help with the investigation.
Authorities have not yet ruled out any motives behind the bombings, the prime minister said, adding that the attacks were intended to damage the country's reputation.
The premier said that soldiers will also be deployed to help maintain order, though there was no need to invoke any special laws to control the situation. He was referring to the Internal Security Act and the emergency decree.
Gen Prayut said that no bombings had occurred during his first five-year term as prime minister after the coup.
"Why did they occur during the Asean foreign ministers' meeting?" the prime minister said.
Observers noted that the attacks had only taken place after Gen Prayut relinquished his special powers under the all-powerful Section 44 because he stepped down from the role as the chief of the now-defunct National Council for Peace and Order, which ceased to exist after the new government was sworn into office.
A message posted on the prime minister's Facebook page said: "I condemn the mastermind behind this morning's bomb blasts, which destroyed people and the country's image. I have asked officials to beef up security for members of the public and take urgent care of those affected by the explosions.''
Foreign Affairs Minister Don Pramudwinai said that the bombings had not affected the Asean Ministerial Meeting and the event will proceed as planned.
"We do not know yet how many people are involved," Deputy Prime Minister Prawit Wongsuwon told reporters, adding that "People who do it want to stir the situation".
The bombings took place just before a keynote speech was delivered by Mr Pompeo.
