A Thai television station has apologised for re-enacting a blast at a shrine in Bangkok that killed 20 people on Monday, and threatened to discipline those employees behind the plan, the BBC reported on Friday.

The re-enactment on Thursday, which featured a Nation TV employee dressed as the main bomb suspect, had sparked outrage, forcing the station's executives to issue an apology.

The TV station's presenters read an apology on TV on Thursday night, where executives acknowledged the station's actions were insensitive.

The bomb went off on Monday at the popular Erawan Shrine, leaving police scrambling to find the suspect and sending shockwaves through the nation's vital tourism sector.

Just three days after the attack, Nation TV sent out a team to re-enact the bombing, including having a staff member dressed up to look like the suspect, as he was seen on closed-circuit television footage.

But the team had to call off the filming as people at the scene "expressed frustration" at them, the BBC said, citing a statement by the station.

A Nation TV editor, in a statement posted online, said the team was sent out at about 6pm local time on Thursday.

Nation Broadcasting Corporation president Adisak Limprungpatanakij said in another release that the re-enactment was made "without consideration for the sensitivity of the public and with disrespect for the dead", .

He added that the Nation TV may punish those behind the incident.

Twitter user BoyOfHeaven posted pictures on Thursday evening that appeared to show Nation TV staff during the re-enactment.

"There is an unidentified TV crew, they have someone dressed as the suspect in the shrine. Police have asked him to leave the scene and people are shouting 'terrible' at him," he said in a tweet that went viral online, causing an uproar.

Police chief Somyot Poompanmoung told AFP that his officers were making "a lot of progress" in the hunt for the bomber despite the lack of arrests and a mystery over the attackers' motives.