Firefighters worked to put out a fire on the second floor of the Bath Arms Hotel after it broke out about 5.45am today.

Heavy smoke was seen wafting from the venue and the front room of the building was completely engulfed in flames.

One accommodation room in the two-storey pub was completely burnt out in the blaze, which took 35 firefighters and eight fire trucks to put out.

“If anyone was inside this would not have been survivable when our firefighters got here,” FRNSW Superintendent Adam Dewberry said. 

“Fortunately, the occupant had already left for work.”

About 20 people were evacuated and the fire brought under control in about 20 minutes.

There were no injuries recorded.

Fire and Rescue NSW is investigating and believe the source could be lithium-ion batteries from vapes.

Multiple vape batteries were found on charge in the room, FRNSW said. 

Dewberry said the occupant confirmed he left “cheap-style” vape batteries charging in the room.

Dewberry said the batteries were very flammable and could catch fire during a blaze even if they are not the source.

“They are extremely volatile and explosive and can significantly increase the intensity of the fire,” he said.

FRNSW warned people to never leave lithium-ion-powered devices charging while you sleep or are away from home.