A push by restaurant owners to slash weekend pay for staff would ultimately lead to a wages cut for more than half a million low-paid workers, the union representing employees in the industry says.

Restaurant and Catering, which represents owners and managers in the industry, will appear before the industrial relations commission in Sydney on Tuesday.

Only hospitality workers who work more than five days in a row would get penalty rates under proposed changes. Credit:Jessica Shapiro

Chief executive John Hart will present the industry's case to cut the extra payments for hospitality employees who work weekends and nights.

Instead, only those who work more than five days in a row would get the penalty rates they are now entitled to.