Construction employers have launched a push to scrap Saturday penalty rates until the end of the year to deal with the economic impact of the coronavirus.

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.

Under the proposal, 38-hour ordinary working weeks could be performed between 6am and 7pm Monday to Friday and 6am and 2pm on Saturday.

Casual shifts could be as short as two hours, while workers and bosses could agree to time off instead of overtime.

The CFMEU argues the pandemic is being used to attack wages and conditions, accusing employer groups of opportunism.

The construction union is opposed to changing the award.

Chief executive Denita Wawn said many building contracts signed before the onset of coronavirus were based on high productivity.

“We have had to slow down because of social distancing,” she told Sky News on Tuesday.

“We’re simply asking that by agreement, that employer and employee can come to an arrangement in a temporary way until the end of the year.”

She said a predicted 40 per cent decline in work could hit a third of workers in the sector, putting 450,000 jobs on the line.