At least eight people have died and seven others were hospitalised after fire suppression chemicals were accidentally released at a bank in Bangkok.

The Bangkok Post newspaper says the accident at the Siam Commercial Bank's head office happened at 9.30 last night local time.

The report said smoke from the bank's basement prompted the fire extinguishing system of the building to release the flame retardant, killing eight people on the spot.

The bank has issued a statement blaming the accident on contractor negligence.