The eight were killed after the building’s fire-prevention system accidentally released pyrogen, which is widely used as a fire extinguisher. The aerosol fire retardant vapourised, depriving a room in the bank’s basement of oxygen. Seven others were affected. Most of the victims were working on the fire-prevention system to improve it.

Two executives of Mega Planet, which was in charge of improving the system, have been charged with recklessness leading to the death of others.

Yesterday, the Criminal Court approved arrest warrants for five more suspects, as the ongoing police probe suggests that more people should be held responsible for the incident.

The warrants were issued for Jirawath Prempree, an engineer at Mega Planet, Tripop Yangprasertkul, a manager at Jones Lang LaSalle; Kajornjit Promdeerach, an employee at Abit Multi System; Somkid Tan-ngarm and Somkid Chanhom, employees of Jones Lang LaSalle.

Jirawath is supervisor of the project to improve the fire-prevention system at the bank. He went to Phaholyothin Police yesterday with Mega Planet lawyer Suriyes Songmeechai.

Both denied reports that the firm had assigned untrained employees to carry out the work at SCB headquarters.

“All of them had received training from Jirawath before they headed to the site,” Suriyes said. The lawyer said Mega Planet wanted to know why the workers did not escape. “But after the accident, we were not allowed to enter the place.”

Jirawath said he had advised all Mega Planet employees about characteristics of the SCB worksite including spots to avoid and where the fire exits were located.

“We have worked here since last September. Our project is already more than 90 per cent complete,” he said. Jirawath was not at the scene when the accident happened.

“But there’s a foreman to oversee the team,” he said.