Despite consistent pressure and criticism from Labor, the government is yet to dip into the Emergency Response Fund, which has gained more than $800 million in interest since its inception.

Mr Morrison declared the floods a national emergency and announced millions in support measures on Wednesday, however none were funded by the Emergency Response Fund, despite being specifically mentioned by the Prime Minister.

READ MORE:

"It's crises like this that the Emergency Response Fund was established to help support and it will help as part of the initiatives we deliver, so communities across NSW and Queensland get back on their feet," Mr Morrison said.

The $4.8b fund was established in 2019, and allows for up to $150m a year to be spent on emergency response and recovery, and $50m a year on disaster mitigation. However, only $100m has been offered up to fund two rounds of flood mitigation projects, none of which have started construction.

The government has defended its use of the fund, which is designed to be a fund of last resort when other funding measures are insufficient.

A spokesperson for Emergency Response Minister Bridget McKenzie said the federal government had already offered more than $863 million in support for the south east Queensland and NSW floods since February.

Mr Morrison and Senator McKenzie said the ERF would be used to support flood mitigation projects around the Northern Rivers region.

"The things that will actually help save people here in flood events like this is the sort of mitigation and other works that frankly, haven't been done here for some time, and it's been a frustration over a long period of time," Mr Morrison said.

"So that's why I'm saying; it's time to get over there and to get it done. If further hydrology work is required, then we will support that with additional funding. This isn't about 'if', this is about 'what and when'.

"The Emergency Response Fund of the Commonwealth will be used to support those works. I'm not talking tens of millions, I'm talking more than that. Those costings will be settled between the Commonwealth and the state government and local governments to the extent that they're able to contribute."

Labor has promised to spend $200m from the ERF on disaster mitigation every year if elected. Labor emergency and disaster management spokesperson Murray Watt said he's been asking the government for years why it wasn't using the fund to build flood levees, drainage systems, bushfire evacuation centres.

"It's pretty strange that even after unpreceded flooding, Scott Morrison still hasn't used the $4.8-billion fund - it was set up three years ago and not a cent has been spent on disaster recovery," Senator Watt said

"I'm pleased to see that finally, Scott Morrison is flagging he will use his Emergency Response Fund. It's a shame that he's only prepared to use it when an election is around the corner.

"People needed this fund to be used in the lead up to the floods, not just when it suits him for an election."

The latest package of flood support includes $25m for emergency relief, $41m in mental health support and $7m for business recovery and resilience services.