Seven new cases of COVID-19 were recorded overnight for WA, including four mystery cases, the Premier announced on Friday, along with new mask-wearing rules for Australia Day events.

Three of the seven local cases are known contacts of previously reported cases and were potentially infectious in the community.

The remaining four are currently not linked directly to any previous cases, however they remain under investigation by contact tracers.

“We believe there could be a link but we’re not certain at this point,” McGowan said. “They are all in self-quarantine now and public health will continue to monitor them.”

The Premier also announced that masks will be required at all public Australia Day events.

“Australia Day is only four days away, we want all events to proceed safely,” he said.

“Therefore, for all public events on Australia Day, mask-wearing will be required for both indoors and outdoors.”

The update comes a day after the Premier announced that the state’s February 5 reopening would be delayed.

McGowan said WA reopening as planned would be “reckless and irresponsible” given the large number of cases in the eastern states.

The February 5 reopening was based on modelling which, at the time, didn’t take the Omicron variant into account.

No new date has been set for when the state may relax its hardline border measures.

Meanwhile, Australia has recorded its deadliest day of the pandemic.

There were 88 virus-related fatalities reported across the country on Friday, eclipsing the previous record of 78 set on Tuesday.

More than half of the deaths on Friday were recorded in NSW, which had 46 fatalities, a one-day record in the state.

Of the 46 fatalities, seven were from historical cases and had been determined as COVID-19 deaths following coronial investigations.

NSW also confirmed the death in December of an infant with COVID-19, although that fatality has not yet been recorded in official figures pending the conclusion of a coronial investigation.

There were a further 20 deaths in Victoria, 13 in Queensland and one in Tasmania, the state’s first COVID fatality for almost two years.

There were two deaths in the ACT, an equal high for the pandemic, along with six in South Australia.

Across the country, there were 25,168 cases in NSW, 18,167 in Victoria, 16,031 in Queensland, 3023 in South Australia 866 in Tasmania and 826 in the ACT.