Fire and Rescue NSW crews arrived at the scene about 7.30pm after receiving multiple emergency calls.

Duty commander Inspector Kernin Lambert said staff first reported a strong smell of smoke in one area of the hospital before other staff reported a gas smell on the opposite side of the building two minutes later.

This led firefighters to believe there could have been an electrical fire in the building.

Inspector Lambert called in reinforcements from Bellbird, East Maitland and Rutherford to assist the crews from Cessnock and Kurri Kurri that were already on scene. Police and ambulance also responded to provide assistance.

Firefighters and the hospital engineer quickly got to work trying to find where the smells were coming from.

They examined each part of the hospital with heat detection camera and gas detectors several times, but after more than two hours they could not find anything.

Inspector Lambert said the odour was strong when crews first arrived, but diminished during the two hours.

“After a thorough investigation I was satisfied there was not a fire,” he said.

Inspector Lambert believed the smell may have come from hospital heating units, which can produce odours of unusual burning when they are switched on for the first time at the beginning of the colder months.

He said any dust that had accumulated on the units may have burnt, which could have caused the smell.

Inspector Lambert praised the hospital staff for their quick action and cooperation.

There was no need for any evacuation and the hospital ran as per usual during the operation.

“They were absolutely fantastic,” he said. “There was no sense of alarm, no sense of panic.”

Inspector Lambert said it was a lesson for people to always call triple-0 if they smelled a burning odour.

He said people often said they smelled smoke several hours before large fires but did nothing because they weren’t sure if there was a fire or not.

“If in doubt, get the brigade out…it’s better to be safe than sorry,” he said.

Inspector Lambert said while the hospital situation was a false alarm, it could have been much worse.

“If something did escalate we were ready for it,” he said.