THE only part of the Mount Warning Hotel left standing after a blaze on Saturday night was gutted in a second fire.
The Uki pub's back building erupted in flames believed to be caused by smouldering ashes.
Murwillumbah Rural Fire Service Inspector Keith Moss said he was surprised when he received the call to the historical building in the early hours of Monday morning.
"I thought it was a hoax," he said.
"It was pouring rain and I was surprised."
NSW Fire and Rescue and RFS were sent to the scene at about 2.22am where they found the back of the building completely alight.
"It was too dangerous to put anyone near the inside of it," Insp Moss said.
NSW Rural Fire Service Inspector Bob Wilcox said the blaze was in no way suspicious despite rumours circulating.
"There's no evidence it was a new fire," he said.
"We had a lot of units here and a lot of resources."
Smouldering ashes most likely caused the second fire to ignite.
"It is extremely hot in places," Insp Wilcox said.
Publican and Murwillumbah resident Geoff Brown said he couldn't believe it had ignited again.
"The neighbour called the fire brigade," an exhausted Mr Brown said.
"I just stayed home; they said there was no point coming out."
The original fire is believed to have been caused by a faulty electrical box.