A coalmine fire blanketing a Victorian town with thick smoke and ash will take at least another two weeks to put out.
Victoria's Fire Services Commissioner Craig Lapsley says another fortnight is the best case scenario to extinguish the fire in the Hazelwood open-cut mine in the Latrobe Valley.
Mr Lapsley said on Tuesday the fortnight prediction was based on it taking the past 12 days to put out more than half the fire, but a day of adverse weather could lead to a significant extension of the blaze.
"On the best case scenario it's two weeks based on the success of the last 12 days but we're up against something that could extend past that and obviously will cause us significant problems if that's the case and ongoing major concerns for the Morwell community."
Burning embers from the fire caused a grassfire near the Hazelwood Power Station which firefighters quickly brought under control on Tuesday afternoon, a State Control Centre spokesman said.
Fires on the conveyor belts have also been brought under control.
"They were worried that there was a risk towards any fires going inside or closer to the power station but that hasn't happened," the spokesman said.
A deliberately-lit fire spread into the mine on February 9 and is now burning over three kilometres in worked-out areas.
The fire is sending thick smoke into Morwell, home to more than 13,000 people.
Authorities have given 25,000 face masks to locals in the Latrobe Valley but say there's not expected to be long-term health effects.
Mr Lapsley said Thursday next week will potentially be another "spike day" where there may be severe fire danger in parts of the state.
"Victorians need to understand that although we've already had fires, that we still have potential weather that could see fires move uncontrollably through the landscape."
Firefighters continue to battle fires in the state's far east that have burned more than 130,000 hectares between the Snowy River and NSW border since mid-January.