Construction employers have been told to "dial it the hell down" after pushing to scrap Saturday penalty rates and slash casual shifts.
Union boss Sally McManus, who has agreed to work with business groups on industrial relations reforms, said the proposals were poorly timed.
Ms McManus said the attack on workplace rights was completely at odds with the tone and spirit of the coronavirus working group.
"We think that is a wrong decision by the employer groups and we'd ask them to withdraw," she told reporters in Sydney on Wednesday.
"We think employers should dial it the hell down when it comes to attacking workers' rights."
Master Builders Australia, Housing Industry Association and Australian Industry Group have made a joint submission to the Fair Work Commission asking for temporary award changes.
Their proposals are primarily aimed at overtime payments and casual shifts.
The groups argue the temporary changes would only need to be in place until the end of the year.
But the construction union argues the pandemic is being used to attack wages and conditions, accusing employer groups of opportunism.
Australian Associated Press