ABOUT 150 acres of pine forest at Lololo Pine Station in Lautoka were destroyed by fire over three days before New Years Eve.
This is in addition to the 300-acre region set alight over the Christmas weekend.
Lololo Pine firefighter Osea Bilo said they were watching three other places within the area that were close to a residential area - Vakabuli, Drasa and Nalotawa.
Mr Bilo believers the fires were started by careless people playing with matches.
"We have reported the matter to the police and also given statements but no action has been taken yet," he said.
"We have finally been able to contain the fires that started the last weekend through till Thursday. But now we can see fires are starting up elsewhere."
Fiji Pine Limited's operations manager Peni Were said the arsonists appeared to have lit the fires for fun, ignorant of the fact that their criminal acts caused immense strain on firefighting resources deployed since last week.