The Rural Fire Service says the Defence Department has been fully cooperative amid claims an Army training exercise caused the state’s largest blaze.

An RFS investigation has found that live ordnance training last week at Marangaroo caused the State Mine Fire near Lithgow, which has now burnt almost 50,000 hectares and destroyed at least three homes.

The ABC understands that at least two other fires in Queensland and South Australia have been linked to live fire Defence training exercises in the last three months.

The Defence Department says its own investigation is underway about the State Mine blaze and it is yet to accept the finding by RFS investigators.

RFS Commissioner Shane Fitzsimmons says he is confident Defence will make the same findings.

“They have been fully cooperative right from the outset,” he said.

“I don’t think they’ve ever shied away from their initial thoughts that they may have been responsible for this. There is no conspiracy here, there is no-one shirking responsibility or ownership that I can see anywhere.”

However, Blue Mountains Mayor Mark Greenhill has been scathing of the Department’s apparent involvement in the Lithgow fire, saying although there was not a total fire ban in place that day the Department should have realised conditions were not ideal.

“It’s done damage to my community and it just shouldn’t have happened. Not happy at all,” he told the ABC’s 7.30 program.

“There’s the damage it does to the community and the stress it causes. There’s the damage it does in terms of the risks taken by the firefighters.

“There’s the damage it does in terms of the costs to the community of fighting that fire and let’s not forget it’s still going, it’s still out there.”

Defence said in a statement it had been conducting live ordinance exercises at the Marrangaroo Training Area the day the fire started.

It said it was cooperating with police and investigators as well as conducting its own inquiry.

The ABC has confirmed that a weekend blaze at the Cultana Army, base near Port Augusta in South Australia, is also linked to Defence live fire exercises. 

South Australian Country Fire Service spokesman Bluey Devine says the service was called on Saturday to extinguish a grassfire on military land. 

Defence live fire exercises are also suspected to have started a fire at the Townsville Field Training Area in Queensland in August. 

That blaze went on to destroy the historic Dotswood Station homestead, built in the 1860s. 

Meanwhile, the RFS has been trying to put in a 20-kilometre containment line to halt the progress of the State Mine fire.

It was one of several blazes that had been subject to an emergency warning during extreme temperatures and wind gusts yesterday.

Fire crews worked through the day on Wednesday to reinforce containment lines around the largest fires in the Blue Mountains, Lake Macquarie and the Southern Highlands.

But despite all being downgraded to watch and act alerts, Mr Fitzsimmons says the danger is not over.

“We do need to be crystal clear here there is still a lot of fire across the Blue Mountains area that is very active,” he said.