Security organisations have been instructed to step up security measures, including inspecting security cameras installed in public areas, especially in large cities, ahead of the third anniversary of the regime seizing power, Deputy Prime Minister and Defence Minister Prawit Wongsuwon said yesterday.
The move follows a bomb blast near Sanam Luang on Monday night.
Bangkok police chief Sanit Mahathavorn, holding the PVC 'explosive' at the scene of the small blast, said Monday it was no bomb. He changed his mind after the top security chief, Deputy Prime Minister Prawit Wongsuwon, said that it was an explosive. (Photo by Apichart Jinakul)
"As the third anniversary of the government and the National Council for Peace and Order draws near, certain groups are attempting to discredit the government and the NCPO," Gen Prawit said after Tuesday's cabinet meeting.
He said certain groups were waiting for the right time to trigger unrest, adding that these groups were, however, small and consisted only of one or two people.
The authorities were monitoring these groups, but he couldn't reveal any further information about them at this point, said Gen Prawit.
- Earlier report: Police chief Sanit: It wasn't a bomb
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Gen Prawit was speaking following Monday night's explosion in front of the National Theatre near Sanam Luang, in which two women were slightly injured.
The police investigation team probing the incident, meanwhile, found a key piece of evidence identified as an "IC timer", which suggested the explosion was linked to the April 5 explosion in front of the old Government Lottery Office (GLO) which also injured two people, according to an informed source.
The investigation team surmised from the IC timer that the person behind Monday's incident and the April 5 blast is likely the same person, and has exceptional skills in bomb making, said the same source.
The bomb in Monday's incident was considerably smaller than the one in the April 5 blast, said the source, adding this was possibly because the bomb maker this time intended for as much evidence as possible to be destroyed in the explosion.
This explained why the police didn't find any trace of explosives in their preliminary investigation of Monday's explosion, said the source.
Not even the material that is usually wrapped around the explosive remained after the blast, the source said.
The source also said the PVC pipe pole supporting the board displaying the layout plan of Sanam Luang broke most likely because the bomb had been planted near the pole.
Under the circumstances, the investigation team surmised that the attacker only intended to stir up unrest, but did not aim to cause any deaths, said the source.
On April 5, an explosion outside the old GLO on Ratchadamnoen Klang Avenue, wounded two women.
Some PVC piping, metal shards and a timer were recovered at the scene of the explosion.
Police then believed they were parts of a low-impact pipe bomb which was designed to cause panic rather than claim lives or cause injuries at the scene.
An initial examination suggested the bomb was similar to one that exploded in a telephone booth near the Major Cineplex Ratchayothin in 2007, according to a police officer close to the investigation.
Prime Minister Prayut Chan-o-cha reportedly instructed his deputy, Gen Prawit and the NCPO to speed up the investigation into Monday's incident.
"If it's found to be an attempt to trigger panic, then the culprits must be brought to justice" said Gen Prayut.
"Please don't panic. The authorities are ramping up their work to figure out what caused the explosion while at the same time working to ensure public security," he said.
On Monday, Chana Songkhram police were alerted to the explosion at around 9pm and an explosive ordnance disposal (EOD) team was sent to examine the blast scene.
The two victims were identified as Chanphen Wutthi-ekphaibun, 54, and Kanchana Bunchip, 38, who suffered light injuries caused by PVC shrapnel along with ringing in their ears.
They were given first aid at a nearby tent where army medical staff help visitors to Sanam Luang. Ms Kanchana said she was waiting for a bus with about 10 other people when the explosion occurred, sending white smoke billowing up through nearby trees.
She said she had just been to the Grand Palace to pay her respects to His Majesty the late King.
Following Monday's incident, deputy national police chief Pol Gen Srivara Ransibrahmanakul said he had ordered the Metropolitan Police Bureau to check security cameras installed near the blast site.
Pol Gen Srivara said at this point, there was no clear indication to whether the explosion was an attack or simply an accident, and the public should wait until a definite cause had been identified.
Deputy Bangkok governor Amnoy Nimmano said the Bangkok Metropolitan Administration has high-quality security cameras in the Sanam Luang area and will send their footage to investigators.
First Army commander Lt Gen Apirach Kongsompong also said he suspected that the Monday night blast was a fresh attempt to stir unrest, as was the April 5 incident.