"We have recovered 27 bodies, others are being sent to hospital," Prime Minister Anutin Charnvirakul said on Monday.
The fire broke out around midnight on Sunday (3pm AEST).
The pub in Bangkok's Chatuchak district rapidly filled with smoke after a fire broke out around midnight on Sunday (3pm AEST), forcing many to run to the back of the venue near the bathrooms, but there were no fire escapes.
Another 63 people injured in the incident have been hospitalised, said Suriyachai Rawiwan, director of the Bangkok Metropolitan Administration's Department of Disaster Prevention and Mitigation.
"The number of deaths has stabilized at 27," he told Reuters.
By the time the rescue workers arrived at the scene of the accident, the fire that witnesses said ignited at the front of the venue's stage had already burned through the area, according to Suriyachai.
"We have to wait for the police to investigate," he added.
In the early hours of the morning, emergency personnel remained at Rong Beer Na Lat Phrao pub as bodies were prepared for transport and forensic teams collected evidence to help identify the victims.
Numbered bodies lay in two rows awaiting removal, surrounded by a large number of rescue workers. Firefighters stood near the pub's entrance, its facade scorched and blackened by the blaze.
A band member at the venue told local media that smoke suddenly filled the room after the lights briefly went out, followed by a massive explosion and fire.
"After the explosion I didn't see anybody trying to run, most of them were on the floor asking for help," he told reporters, his head still bandaged, without giving his name.
"I ran towards the door from the stage, about five metres. It was dark and there was smoke, no oxygen."
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