WA's peak union body has warned around 60,000 Western Australians can expect a further drop in their pay due to a looming penalty rate cut set for next month.

On July 1 penalty rates will be reduced by a further 10 per cent, and in some cases, 15 per cent.

The rate cut will affect those working in WA's fast food, retail, hospitality and pharmacy sectors, and since the decision was made, Australia's union bodies voiced their anger over the perceived impact the rate cut would have on some of the country's most vulnerable workers.