Bangkok blast: Thai police release detailed sketch of bombing suspect in video

Meanwhile, the shrine that was the scene of Monday’s deadly attack reopened to the public on Wednesday.

The man is seen carefully removing his backpack inside the shrine – at the spot the bomb went off – then getting up without it and immediately leaving.

Police later said two other people seen on CCTV were being treated as suspects.

“He seemed not in a hurry at all”, the driver said, adding that the suspect handed him a note that read, “Lumpini Park”.

The man could be of “mixed origin”, Prawut said in a televised interview.

“We believe there must be people helping him, Thai people”, he said.

But he revealed no other details.

But apart from the rough portrait, they had few solid leads in Monday’s bombing at the Erawan Shrine that killed 20 people and wounded 120 others.

Those killed included several Thai victims, six Chinese, a Malaysian family of four, an Indonesian, a Singaporean woman, and a British teenager.

Sixty-eight people remained in hospital, 12 of whom were in critical condition.

Reuters says the police described the suspect as being fair-skinned – he could be from the Middle East or Europe – and that he had dark hair, black glasses, and a beard.

He said: “There have been minor bombs or just noise, but this time they aimed for innocent lives”.

An arrest warrant was issued for the unnamed bespectacled suspect, who was filmed on security footage placing a backpack at the shrine before Monday’s blast that tore through the popular tourist site.

The BBC’s Steve Evans in Bangkok says the new information implies this may have been an organised worldwide operation, perhaps with a religious motive.

Prawut told reporters Wednesday night that police would continue to scrutinize closed-circuit TV footage of the area from before the blast for clues about suspects.

“I am confident that there are Thais involved but I am not saying it is just Thais or that there are foreigners”, he said.

Local authorities have appealed for anyone with information surrounding the alleged bomber to come forward, offering a reward of one million Baht (the national currency) – equivalent to roughly AUD$40,000.

In the early evening on Tuesday, a small explosive device appeared to have been thrown towards a pier from the Taksin bridge in the Thai capital, heightening concerns about continuing strikes on the capital.

Security experts had previously said they were baffled over who was responsible.

National police spokesman Prawut Thawornsiri said: “These types of attacks are not usually planned by one person alone”.

“I’m still scared because you never know where [the perpetrators] will strike again”, 43-year-old Sommai Gazem said.