Sanit said a police review of CCTV recordings in the area had been “useful” but declined to elaborate. He also instructed police investigators to gather evidence and report back to him on Friday afternoon.

Sanit also urged the members of public to not jump to conclusions or link the incident to politics pending the police investigation.

Sanit said police had not found any links to previous bombings in Bangkok, while urging city precincts to boost security measures as a precaution.

His comments were made after an urgent one-hour meeting at the Chanasongkram Police Station on Thursday morning. Sanit also inspected the explosion scene again and expressed his opinion that the fragments found were similar to those found after a blast damaging telephone booths in front of Major Cineplex Ratchayothin. No one was injured in that attack.

Police said they suspected that the explosion, which took place at 8pm inside a garbage bin in front of the old Government Lottery office and was initially believed have been a low-pressure pipe bomb, was aimed at creating chaos.

The blast slightly wounded two people who were standing nearby. Suriyaporn Poolsombat, an employee of the Bangkok Metropolitan Administration (BMA), experienced a ringing sound in her ears while Pimwar Raweenoppasit, another BMA worker, had scratches on her arm.

Earlier in the morning, police forensic officers along with the Explosive Ordnance Disposal team collected evidence at the scene including metal pieces and an electrical circuit panel.