POLICE are assisting fire authorities with an investigation into a bushfire believed to be deliberately lit north of Grafton.
Rural Fire Service and National Parks crews continue to fight the blaze in the Fortis Creek National Park, after being alerted on Wednesday afternoon.
"It appears the fire at Fortis Creek has been deliberately lit," Clarence Valley Rural Fire Service district manager Superintendent Stuart Watts told The Daily Examiner this morning.
"NSW Police will be involved in the investigation into the cause and origin of the fire.
"The fire took a bit of a run yesterday."
Rugged terrain and fierce heat from the thick and dry vegetation fuelling the fire has made it difficult for fire crews to control the blaze.
"The fire has been fierce and erratic which has made it challenging to bring under control," Supt Watts said.
"The topography doesn't lend itself to easy containment."
Yesterday the storms which swept through the Clarence Valley played havoc with attempts to control the fire.
Today favourable weather conditions are so far helping fire crews make progress. However, storms are again predicted for this afternoon.
"The wind shift from the storm cells that came through yesterday afternoon drove the fire outside our identified containment lines," Supt Watts said.
"It took the fire fairly close to private property.
"Today will be a day of reassessing potential for those containment lines and preparing for any large scale backburning operations.
"It seems the weather is on our side today. At this point it is overcast and relative humidity is a bit higher.
"They're predicting storms in the afternoon. If we're lucky enough to be under a storm that delivers rain it may slow the fire down.
"But on the other hand it may hinder us with lightning strikes or only receiving just enough rain to stop any backburning operation."
The Fortis Creek fire is one of several currently burning in the Clarence Valley. The most visible fire to the public is at Dirty Creek, which is currently under control but in close proximity to passing motorists on the Pacific Highway.
"There is a smaller fire in the Dirty Creek Range area on the southern border with Coffs Harbour district," Supt Watts said
"It has been brought under control but will put some smoke across the highway over the next couple of days."
Two more fires in the Upper Clarence Valley have been burning since the weekend but have been brought under control by fire authorities.
"If anybody sees a fire with no fire unit in attendance they should call triple-zero," Supt Watts said.
"If anyone sees any persons acting suspiciously in the bush they should also contact police.
"We advise people to look at our website which has a fantastic catalogue of information on how to prepare for fire and what to do when fire breaks out."
If anyboyd sees an unatteneded fire with no fire unit in attendance they should ncall triple-zero. If anyone sees any persons acting suspiciously in the bush should contact police.
Campers were forced to evacuate camp sites at Station Creek and Pebbly Beach during the recent school holidays due to a large bushfire in scrubland along the Clarence Coast southeast of Grafton.