He labelled his own lavish nuptials "Australia's best wedding". Now colourful former Auburn deputy mayor Salim Mehajer is promising to outdo Rebel Wilson and launch Australia's biggest defamation case.

Sydney solicitor Zenah Osman, the low-profile sister of the 31-year-old property developer, said in a letter to Fairfax Media on Saturday that her brother and his "related entities" intended to launch defamation proceedings against a range of media outlets.

Record payout: Salim Mehajer says he will sue Australian media outlets for $103 million. Credit:Christopher Pearce

"Being in the media spot light [sic] is tough and brutal. One must be very patient and enduring," Mr Mehajer said in a statement.

"I let the media throw in all the punches for the past twenty months and watched my case build just like a business deal. I think now though, it has reached its peak and its [sic] time I commenced legal proceedings. All proceeds will be donated to charity."