PM to visit flood-ravaged Lismore in NSW

Lismore has been among the regional areas devastated by the floods, where four people have died, hundreds displaced and thousands of homes and businesses destroyed.

The prime minister is expected to announce more funding to help rebuild communities, with a focus on long-term reconstruction projects.

"The flooding disaster across south-east Queensland and NSW is absolutely devastating," Mr Morrison tweeted on Tuesday.

"While the clean-up and recovery is well underway for some, many areas particularly around Lismore remain isolated ... and critical supplies being airlifted in."

There are 1800 ADF personnel on the ground in northern NSW assisting flood recovery efforts, with that number set to grow to 2500 by the end of the day.

Brigadier Robert Lording, who is on the ground in Lismore on Wednesday, told Sydney radio station 2GB that figure would increase to 4000 by week's end.

"The scale of this incident has been far bigger than anything we've potentially experienced in this area before," he said.

"It's a large logistics effort to get people up here, and importantly, it's a big logistics for us to get the money here and to be able to support them."

Residents in Lismore and surrounding areas have criticised the government's handling of the crisis, calling the response too slow to help deal with the clean-up efforts.

Agriculture Minister David Littleproud said the prime minister wanted to see the impact of the floods in northern NSW, despite the frosty reception he could receive from locals.

"I'm sure the prime minister, whether he's clapped or booed, wants to be there to understand and to be able to fix the catastrophe that's unfolded," he told Sky News on Wednesday.

"That's his job and he's got to do it whether he's liked or not."

There have been issues with physically getting ADF personnel into areas where access was limited or non-existent due to floodwaters and intense weather conditions.

As of Tuesday morning, more than $282 million in disaster payments to flood victims have been paid to 242,000 people.

Of that, $157 million has been paid to victims in NSW and $125 million in Queensland.