S&P ratings agency said on Monday that Australia's pristine 'AAA' sovereign rating is not at "immediate risk" from the fiscal and economic impact of bushfires.

"We do not believe that these bushfires will affect credit metrics enough to trigger rating changes in the next one to two years," said S&P Global Ratings credit analyst Anthony Walker.

Ratings on the east coast states of New South Wales and Victoria - the most ravaged by the fires - were also likely to be unaffected, S&P said.

"We believe there is capacity within our current ratings on the sovereign and state governments to absorb the fiscal costs, which are relatively small compared with their budgets," Walker added.