THE Rural Fire Service (RFS) will work with police to investigate the cause of two small fires on the outskirts of Orange in the past 24 hours.

While a small fire on Ophir Road was extinguished on Monday afternoon a short time after it started, one on Lower Lewis Ponds Road continues to burn eight kilometres north east of Clifton Grove.

RFS fire investigator Steve Smith said the Lower Lewis Ponds Road had burnt out five hectares but was now under control.

"There's still a fair bit of timber burning and some bee hives have been lost," he said.

Mr Smith said the fire didn't jump to the other side of the road and had been contained to one area.

He said investigators are yet to determine the cause of the fires.

"Not all fire investigations are because fires are suspicious, sometimes they're started by something as simple as the exhaust from a truck."