The NSW Rural Fire Service (RFS) is treating a bushfire in the Blue Mountains, west of Sydney, as suspicious.
Specialist firefighting teams have been enlisted to help tackle the blaze, which is being fanned by gusty winds.
While there is no immediate threat to homes in the area, it was upgraded to an emergency warning level this afternoon before being revised back to a watch and act as authorities worked to control the blaze.
RFS advised people in the area of Coronation Road to seek shelter as the fire approached.
RFS Inspector Ben Shepherd said it may be a number of days before the cause of the fire was known.
“Given the absence of any natural causes, we are treating the fire as suspicious,” Mr Shepherd said.
“Not necessarily deliberately lit, there is word that this area is quite common with campers so we have to rule things out like escaped campfires.”
Meanwhile, Mr Shepherd said winds were expected to strengthen throughout the afternoon.
“There may be gusts once again upwards of 70/80 kilometres an hour,” he said.
“Our firefighters stand ready and the helicopters are doing what they can but it is a bit of a waiting game till conditions are more in our favour to start aggressively attacking this fire.”