Lungs of the world on fire in Amazon: PM

Scott Morrison has declared the "lungs of the world" are burning as escalating fires ravage the Amazon rainforest.

"It's very distressing," the prime minister told Sky News in an interview aired on Wednesday.

"It's often been described as the lungs of the world and they are on fire."

Leaders of the world's seven largest economies have offered Brazil $30 million to help fight the Amazon fires.

But Brazil is poised to reject the "colonialist and imperialist" offer from the G7 nations.

Mr Morrison has again indicated Australia is likely to leave the massive firefighting battle to others, as it focuses on the upcoming bushfire season at home.

"We'll carefully consider what requests are made - we're concerned like everybody else is and we'd look to see what sort of arrangements are put in place," Mr Morrison said.

"But we also have a lot of our own challenges to deal with within Australia."