The State Mine, which is burning from Lithgow to west of Bilpin, was causing firefighters the most concern Sunday, the Australian Broadcasting Corp. reported.
"We're planning for the worst but hoping for the best," Premier Barry O'Farrell told the Australian Broadcasting Corp.
Rural Fire Service Commissioner Shane Fitzsimmons said the worst thing that could happen would a merger of the three largest blazes.
"The potential is for the entire Blue Mountains and Hawkesbury, including places like Kurrajong, to be at risk over the coming days," Fitzsimmons said. "We genuinely hope not to see a massive evacuation or removal of people out of all these townships. The reality is I expect to see significant relocation of people out of harm's way."
Earlier, O'Farrell said residents would be forcibly removed from their homes if they do not evacuate when conditions get extreme.
"Undoubtedly that will cause distress to those people and wider controversy, but it's clear that at times like this it's better to be safe than sorry," O'Farrell said. "It's better to do the right thing and not have it occur, than not do the right thing and end up with a disaster."
About 50 fires were burning as of Sunday morning, with just under 15 being still uncontained, Joel Kursawe at the RFS headquarters told the ABC.
"We're really working to strengthen and consolidate those containment lines this evening while the conditions are still a little bit benign before the return of those hot, windy conditions over the coming days," Kursawe said.
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