WA's confirmed virus cases surge to 28

Western Australia's RSL has cancelled Anzac Day services to slow the spread of COVID-19

Confirmed coronavirus cases in Western Australia have surged to 28 after jumping by 10 overnight.

Premier Mark McGowan said all of the new cases were Perth residents.

"Travel information is still pending for most cases: one recently reported returning from Hawaii, there are two sets of linked husband-and-wife cases," Mr McGowan told reporters on Monday.

One person is in a serious but stable condition in hospital.

The state government announced a $607 million economic stimulus package, including freezing household fees and charges, and doubling the emergency assistance payment to $600 for eligible concession card holders.

It also made available up to 20 days' COVID-19 leave to all public sector workers who have exhausted their paid personal, carers or sick leave entitlements.

WA joined NSW, Tasmania and Victoria in cancelling Anzac Day services to reduce the coronavirus spread.

Western Australia's RSL announced the cancellation - the first since 1942 - after the federal government banned gatherings of more than 500 people. It will also include smaller regional events.

Last year, about 30,000 people attended the Anzac Day dawn service at Kings Park and an estimated 10,000 people later lined Perth CBD streets for the march.

"We need to defend ourselves and do the right thing, not only for our veterans, many of whom are older people, but also their families and the general public," RSLWA chief executive John McCourt told 6PR radio.

He said plans were under way for some sort of live-streamed commemoration that the public could watch via social media.

WA schools have introduced precautionary measures including cancelling events and staggering recess and lunch breaks to slow the spread of the disease.

The McGowan government declared a state of emergency on Sunday, warning overseas arrivals who breach the 14-day self-isolation period will face the nation's toughest penalties with fines up to $50,000.

Mr McGowan urged people to report anyone defying the ban to police.

"Public health officers, with the assistance of police, will be able to enforce it."

He said authorities had a list of names from airlines "so there is the opportunity to follow this up".

Jury trials have also been postponed, with those listed to commence in March, April and May to be considered for a trial by judge alone.

The Supreme Court of WA remains open to the public, but it urged anyone other than legal practitioners, involved parties, witnesses and media not to attend.