Authorities said three drops of the pink retardant had helped create a 2.5 kilometre (1.55 mile)-long line of defence along the bottom of a mountain south of Canberra.
The defence line has enabled fire crews to save all structures in the Australian Capital Territory (ACT) so far, with further drops planned for Sunday, ACT Emergency Services Agency (ESA) Commissioner Georgeina Whelan said on Saturday evening.
“This has been a good firefighting day for us in terms of protecting our cultural assets and critical infrastructure,” she added. “Our intent tonight is to undertake backburning operations to consolidate those containment lines.”
Ms Whelan added that crews were able to save a communications tower on Mount Clear thanks to preparatory work, calling it “a very important win for us today in order to be able to maintain our trunk communications going”.
The New South Wales (NSW) Rural Fire Service (RFS) warned around midnight that there were 62 bush and grass fires burning in the state, with 25 still needing to be contained.
“More than 2,000 firefighters remain in the field,” said the service. “Crews will work overnight to slow the spread of fire and protect homes where possible.”
Earlier on Saturday, there were fears the blazes could reach suburbs in the south of Canberra, whose residents braced themselves for fiery conditions similar to those in 2003.
Around 500 homes were destroyed and four people killed in bushfires that raged in the area in 2003.
A state of emergency will remain in place in ACT until Sunday, with heatwave conditions expected to continue throughout the weekend.
High temperatures exceeding 40C and strong winds could still lead to fire spreading quickly, and authorities urged residents to “remain alert, not alarmed”.
About 55,000 hectares (approximately 135,907 acres) have burnt away in Orroral Valley, where the blazes started due to a military helicopter delivering support for bushfire operations.
The helicopter crew were conducting aerial reconnaissance and ground clearance to enable access to emergency services personnel when heat from the aircraft’s landing light started a grassfire underneath it while it was grounded.
This fire season has brought unprecedented damage since it began in September, killing 33 people and an estimated one billion native animals.
The Australian government has faced criticism for its handling of the crisis, which experts say was exacerbated by climate change that resulted in extreme heat and prolonged drought.
Additional reporting by agencies
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