Firefighters in Australia have managed to keep uncontrolled blazes from reaching suburban areas of the country’s capital city, Canberra, using airdrops of fire retardant.

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.”

Australia fires: Dust storm and flooding that followed Show all 20 1 /20 Australia fires: Dust storm and flooding that followed Australia fires: Dust storm and flooding that followed A child running towards a dust storm in Mullengudgery in New South Wales Marcia Macmillan/AFP Australia fires: Dust storm and flooding that followed Wind gusts of 66 mph were recorded as a dust storm descended over Dubbo. Storms hit many parts of Australia's western New South Wales Ian Harris via AP Australia fires: Dust storm and flooding that followed Hail covers vehicles in an intersection in Canberra. As well as dust storms, hail and flash floods have battered beleaguered Australian cities as extreme weather has diminished the threat from scores of wildfires that continue to blaze across the country's southeast Australia Institute via AP Australia fires: Dust storm and flooding that followed A dust cloud billows over a street in Dubbo Ian Harris via AP Australia fires: Dust storm and flooding that followed A man holds golf ball-size hail outside Parliament House after a severe hail storm hit Canberra EPA Australia fires: Dust storm and flooding that followed A koala holding on to a tree before it was moved to a dryer enclosure during a flash-flood at the Australian Reptile Park in Somersby Australian Reptile Park/EPA Australia fires: Dust storm and flooding that followed Bushland is seen burnt by fire as rain pools in large puddles at Bilpin, in the Blue Mountains AAP Image/Reuters Australia fires: Dust storm and flooding that followed A staff member carrying koalas during a flash flood at the Australian Reptile Park Australian Reptile Park/AFP Australia fires: Dust storm and flooding that followed A dust storm in Mullengudgery Marcia Macmillan/AFP Australia fires: Dust storm and flooding that followed A submerged car on Gold Coast AP Australia fires: Dust storm and flooding that followed Damaged cars parked outside the National Film and Sound Archive of Australia after a hail storm hit Canberra EPA Australia fires: Dust storm and flooding that followed Golf ball-sized hail at Parliament House Getty Images Australia fires: Dust storm and flooding that followed Aftermath of a hail storm at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) glasshouses in Canberra EPA Australia fires: Dust storm and flooding that followed A fallen tree sits on top of a car at Caringbah in Sydney. Storms in New South Wales left more than 2,200 homes without power EPA Australia fires: Dust storm and flooding that followed Damage at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) glasshouses in Canberra EPA Australia fires: Dust storm and flooding that followed Hail stones outside the Parliament House in Canberra Don Arthur/AFP Australia fires: Dust storm and flooding that followed Storm clouds gather over Sydney Harbour AFP via Getty Australia fires: Dust storm and flooding that followed Hail covers vehicles in Canberra AP Australia fires: Dust storm and flooding that followed Flooded fields on Gold Coast AP Australia fires: Dust storm and flooding that followed An aerial view as rain begins to fall on drought and fire-ravaged country near Tamworth Getty Images

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.