Radio shock jock Alan Jones launched a campaign that caused “significant damage” to a Queensland family’s reputation, a prominent businessman has alleged.

The $10 million claim, lodged by one of Queensland’s wealthiest families, related to claims in a series of Mr Jones’ shows that pointed to their culpability and cover-up of 12 deaths in the 2011 floods at Grantham, near Toowoomba.

Mr Jones accused the Wagners of culpability in the deaths because of a poorly constructed levy bank, the law suit claimed, according to News Corp.

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Mr Jones also accused the family of colluding with the state and federal government to “cover-up their culpability”.

Wagners director Denis Wagner said the legal action followed sustained attacks on the family over the years.

“The outcome of proceedings will hopefully in some way go toward correcting the false and defamatory statements about the 2011 Grantham flood tragedy and the Brisbane West Wellcamp Airport that have caused significant damage to the reputation of our family, the operation of the airport and our wider business interests,” Mr Wagner said.

Queensland Premier Annastacia Palaszczuk and Commissioner Walter Sofronoff handed down findings from an inquiry into the Grantham Floods in October. Photo: AAP

The 115-page lawsuit, lodged to the Supreme Court on Wednesday, named Mr Jones, 2GB’s parent company Harbour Radio, Brisbane’s 4BC, and on-air guest and freelance journalist Nick Cater, as defendants.

The lawsuit sought to repair the Wagners reputation and claim compensation for distress and embarrassment.

Mr Jones told The Australian he would not comment, but agreed with Mr Cater, who said: “all of my work on the Grantham floods story was done by me as a journalist acting in the public interest to answer unresolved questions”.

An inquiry into the floods, finalised on October 8, found the structures, including a quarry pit and associated wall owned by the Wagners, were “insignificant” in the natural disaster.

“Both had insignificant evident effect, measurable effects but insignificant, that is to say if they weren’t there nothing would have been different,” the report’s author, Commissioner Walter Sofronoff, said in a press conference at the time.

“I found that the quarry did not play any role in the flood.

“I think they [the Wagners] were unjustly blamed by some people and I think they were viciously blamed by some elements of the media and they shouldn’t have been.”