Broadcaster Alan Jones has denied his radio commentary implied a Queensland family murdered 12 people by their actions during the 2011 Grantham floods.

Jones is being sued in the Supreme Court in Brisbane by four members of the prominent Wagner family, who claim they were defamed when the broadcaster implied they were responsible for the deaths when one of their quarry walls collapsed during flooding in 2011.

The allegations were made in 32 broadcasts aired on radio between 2014 and August 2015.

Jones' employer Harbour Radio, along with 4BC and journalist Nicholas Cater, are also being sued.

In court on Thursday the Wagners' lawyer Tom Blackburn accused Jones of using his radio broadcasts to "convey to your listeners the Wagners had committed murder".

"No, I did not," Jones replied.

"I attempted to convey to my listeners the sentiments of the letter which called it a municipal murder, which in fact is what it is.

"I was intending to say, Mr Blackburn, which I've said for six years, without the quarry 12 people wouldn't have died.

"Without the Wagner quarry, many of these people wouldn't die, it's a self-evident fact."

Mr Jones also rejected Mr Blackburn's assertion that the broadcast was "grossly irresponsible".

"Not it was not. It was perfectly accurate," Jones told the court.

"You called them murderers," Mr Blackburn accused.

"I didn't call them murderers," Jones replied.

Earlier in the day Jones fought back tears as he described the stories of heartbreak told to him by families of the flood victims.

He said residents felt they did not get any answers from a commission of inquiry into the cause of the flood.

"These people would cry when they met me and they really felt they were abandoned and I really tried to give them a pillar of hope," Jones said.

The Wagner family are seeking $4.8 million in damages. ( ABC News: Allyson Horn )

Jones' lawyer, Robert Anderson, asked his client about the broadcasts and whether "those opinions were honestly held by you?"

"They were," Jones told the court.

Comments 'savage', not vicious

Jones admitted his critique of the Wagner family had been "savage" but denied it was vicious.

"I'm saying my criticisms have been accurate," he said.

He claimed he gave the Wagner family many opportunities to speak on his radio program to address concerns raised by residents.

"It was just a blatant no," Jones told the court.

"I was concerned about getting answers for the deaths of 12 people. And it seems that no-one else was prepared to answer that.

"The Wagners didn't appear to be remotely concerned. And that's the Wagner attitude. They want things done their way, well I'm sorry, I do things my way."

Jones told the court he was passionate about the issue, because he was born and raised on the Darling Downs.

"This was the single greatest cause of death in any one environment in the history of the Queensland floods," he said.

"These people had no answers as to how this happened.

"I felt that was a story the nation would empathise with."

The Wagner family is seeking $4.8 million in damages, which would represent the largest defamation payout in Australian history.

The court had previously heard the Grantham Floods Commission of Inquiry in 2015 exonerated the Wagner family over the deadly 2011 floods.

The trial is being heard in front of only a judge.