All the blazes in Australia’s hard-hit state of New South Wales have been brought under control, firefighters said on Thursday, signalling the end of a months-long crisis that claimed 33 lives nationwide.

“As of this afternoon, all fires in New South Wales have now been contained,” a Rural Fire Service spokesman said, as fresh rainfall helped extinguish blazes that have burned along the east coast since September. “It is very good news.”

Blazes scorched more than 10 million hectares in the country’s east and south, killing at least 33 people and an estimated one billion animals while destroying more than 2,500 homes.

The crisis cloaked major cities like Sydney in smoke for weeks on end, saw towns cut off and prompted the deployment of the military to rescue stranded citizens.

Addressing Parliament on Tuesday, Concetta Fierravanti-Wells – a senior member of the ruling conservative Liberal Party and former government minister – called on the nation’s spies to investigate whether eco-terrorists were responsible for the country’s unprecedented bushfire crisis.

Fierravanti-Wells echoed online conspiracy theories to claim it “defies logic” that hundreds of bushfires could have started at the same time.

She claimed that the vast number of fires that started around the same time “not only gave the impression of the possibility of arsonist attack but also suggests a level of coordination.”

“Who are they? What were their motive and intent? Are they lone actors or part of a sinister collective conducting eco-terrorism?” she asked.

Head of the New South Wales Rural Fire Service Shane Fitzsimmons earlier said arsonists were not the main cause of the fires that tore through millions of hectares of south-eastern Australia last year.

“This season has been dominated by natural causes, mainly lightning,” he said in January.

The fires were exacerbated by prolonged drought and worsened by climate change in the country’s hottest and driest year on record.

But days of rainfall – the heaviest in 30 years – have extinguished the largest fires and brought those that remain under control.

Beleaguered volunteer firefighters have fought the blazes day-in-day-out in what has been described as Australia’s “black summer”.

“After what’s been a truly devastating fire season for both firefighters and residents who’ve suffered through so much this season, all fires are now contained in New South Wales,” New South Wales Rural Fire Service Deputy Commissioner Rob Rogers said in a Twitter video.

“Not all fires are out, there’s still some fire activity in the far south of the state but all fires are contained so we can really focus on helping people rebuild.”

In the Australian Capital Territory around Canberra firefighters are still trying to bring one fire under control, but the blaze was not said to be threatening.

Meanwhile, dams near Sydney overflowed on Thursday after days of torrential rain, as the nation braced for more storms expected to bring dangerous flash flooding to the country’s east.

Nepean Dam south of Sydney was at full capacity and spilling over, with video footage showing excess water cascading over the dam wall and downstream.

Two other dams in New South Wales, Tallowa and Brogo, were also overflowing and more dams could reach capacity in the coming days, a WaterNSW spokesman said.

Sydney’s dams have seen water levels spike dramatically – the Nepean was just a third full less than a week ago – though many inland areas are facing severe water shortages missed out on the flows.

Hundreds of people have been rescued from floodwaters in recent days.

Wild weather is set to ramp up again from Friday, with the Bureau of Meteorology forecasting ex-Tropical Cyclone Uesi would bring “damaging to destructive winds” and heavy rainfall to remote tourist destination Lord Howe Island.

Senior meteorologist Grace Legge said storms were also expected for Queensland and New South Wales – with areas still recovering from bushfires likely to be hit again.

“Any showers and thunderstorms that do develop are falling on already saturated catchments, so there is a risk with severe thunderstorms of flash flooding,” she said.

Emergency services have warned residents in affected areas to be cautious in the dangerous conditions.