But first Mr Colvin and Emergency Management Minister David Littleproud are developing an assistance package for businesses affected by bushfires raging across Australia.

The government is currently offering a one-off $1000 payment for bushfire victims, as well as 13 weeks of income support.

Mr Littleproud said he would announce a program in the coming days that will see bushfire-affected businesses eligible for interest-free loans.

"That would then give $500,000 loans -- interest-free, repayment-free for two years -- that will help them rebuild their cash flow, that's an important aspect of it, and it would allow them to even refinance some of their own debt from a commercial bank to the [Regional Investment Corporation] just to give them some breathing space," Mr Littleproud said.

Former Australian Federal Police boss Mr Colvin pledged to listen and learn from victims and committed to long-term support.

"I'm working at the moment simply trying to get my head around the magnitude and the breadth of the areas affected," Mr Colvin said.

"There are people who may not have lost their home but they don't have a workplace to go to. There's businesses who may ... still stand but there's no customers."

In an unprecedented move, more than 1000 Army reservists have been called to help in the bushfire response and that number could reach 3000.

Prime Minister Scott Morrison took a call from US President Donald Trump on Tuesday offering his support and also received messages from UK Prime Minister Boris Johnson.

Mr Morrison has signalled he's willing to sacrifice a federal budget surplus after announcing a $2 billion relief package and has flagged the potential for a royal commission into the bushfires.

Treasurer Josh Frydenberg says more than $25 million worth of relief payments have already been made and promised to limit the "red tape" involved.

Mr Frydenberg said the scale of the fires was unprecedented and there would be lessons to be learned in the aftermath, but could not yet put a dollar figure on the cost of the disaster.

He has instructed insurance bosses to prioritise local tradespeople when they started paying out for rebuilds.

Welfare debt recovery and mutual obligation requirements in bushfire-affected regions are being suspended for at least two months.

The tax office will not chase up returns in bushfire-affected areas for two years, giving people in those areas some breathing space.

Labor leader Anthony Albanese says the $2 billion is a good start but he has been calling for a national approach since November.

"There is no doubt that there will be more investment required," Mr Albanese said.

Liberal backbencher Craig Kelly came under fire for a UK television appearance where he denied the links between climate change and the bushfires.

Mr Kelly later doubled down on the comments he made on Good Morning Britain, where he had also defended the prime minister's handling of the bushfires.

Mr Kelly told the ABC unmet hazard reduction targets and the drought were to blame for the fires.

The prime minister claimed on Sunday his government had always made the connection between climate change and extreme weather conditions.

Australian Associated Press