Peak employer groups have warned business owners against systematic underpayment of workers because it is creating an uneven playing field for those paying lawful wage rates.

Responding to Fairfax Media's investigation into the rampant underpayment of young people in restaurants, cafes and retail, James Pearson, chief executive officer of the Australian Chamber of Commerce and Industry said employers should fulfil their legal requirements to avoid creating unfair competition.

"Thankfully most employers do the right thing, but employers that cut corners hurt operators that play by the rules, posing unfair competition," Mr Pearson said.

"Workplace regulation is a complex web of rules and requirements that many small business owners struggle to navigate without legal help, so non-compliance is not always deliberate."