Western Australia has confirmed five new cases of coronavirus overnight, as the National Basketball League (NBL) says the rest of the finals series, including tonight's game in Perth, would be closed to the public as the outbreak continues to spread.

Key points: The new WA coronavirus cases are mostly from people who went overseas

The new WA coronavirus cases are mostly from people who went overseas The NBL finals game in Perth tonight will be closed to spectators

The NBL finals game in Perth tonight will be closed to spectators WA Premier Mark McGowan wants people to reconsider Bali travel

The NBL's decision came as Prime Minister Scott Morrison and state and territory leaders called for all non-essential gatherings of more than 500 people to be suspended from Monday.

WA chief health officer Andrew Robertson told ABC Radio Perth health authorities were conducting between 800 and 1,000 tests a day in the state, from both GPs and COVID-19 fever clinics, which opened earlier this week.

Last night five more people tested positive, bringing the state's total to 14 cases out of more than 3,780 tests. Only one death has been recorded

"The numbers are actually very small that we are getting from those tests, and the ones that we do have information of have primarily come from overseas," Dr Robertson said.

WA chief health officer Andrew Robertson has confirmed five new COVID-19 cases. ( ABC News: Eliza Borrello )

WA Health Minister Roger Cook said the five new cases were three men and two women aged between their 30s and 60s.

He said all of those people had recently returned from overseas, including from the UK, Europe, the US and Japan.

Mr Cook said authorities were working to determine the flight details of each of those people, which would be placed on Health Department website.

None of those patients were being treated in hospital.

New criteria announced for COVID-19 testing

The WA Government also announced strict new criteria for people who want to be tested for the virus, after half of those who presented for testing at newly established COVID clinics on Thursday were turned away.

Dr Robertson said the COVID clinics set up at Royal Perth, Sir Charles Gairdner and Fiona Stanley hospitals were already under pressure, with half of the people who had turned up for testing being turned away.

"Unfortunately a lot of people turning up for testing probably don't require testing," he said.

"We are turning away around 50 per cent of people that come to the COVID clinics [because they] do not meet the criteria.

Who should present to COVID-19 clinics? People who have EITHER a fever of 38 degrees Celsius OR acute respiratory infection

People who have Symptoms to look out for include fever, shortness of breath, cough or sore throat

Symptoms to look out for include or Patients who are tested should remain isolated at home until they receive their test results. Major clinics have been set up at Perth hospitals including Royal Perth, Sir Charles Gairdner, Fiona Stanley, Joondalup, Armadale, Rockingham and St John of God Midland. They are open from 8:00am–8:00pm daily. In Southern WA a clinic is operating at Bunbury Health Campus from 10:00am–4:00pm daily. In Northern WA a clinic is operating at Broome Hospital from 8:30am–4:00pm daily. Outside these areas, people with symptoms should present to their local hospital. For more information go to the Health Department website.

Deputy chief health officer Robin Lawrence said people would now be required to show evidence of their travel — like a boarding pass, ticket or a bag tag — or provide a name of the person confirmed as having COVID-19 with whom they had been in contact.

She said all testing in the metro area would need to be undertaken via COVID clinic. People in regional areas would still be able to present at traditional health services for testing, but the same strict criteria would be applied.

Dr Lawrence said the decision to enforce stricter rules for testing was due to limited personal protective equipment and testing supplies.

St John WA chief executive Michelle Fyfe said new face masks would be provided to about 700 paramedics who worked in the Perth metro area.

She said the masks might appear "confronting" but they would be important for ensuring the safety and health of all staff.

New respiratory masks will be used by paramedics in Perth. ( ABC News: Jacob Kagi )

NBL finals closed amid events crackdown

NBL executive chairman Larry Kestelman confirmed the remainder of the NBL finals series between the Perth Wildcats and the Sydney Kings, including tonight's game at Perth Arena, would be played behind closed doors.

"The health and wellbeing of our players, staff, officials and fans is paramount. As a family sport we felt this was the only decision to make," he said.

"We will continue to monitor the situation and follow all protocols as outlined by the relevant authorities.

"In the event of a player, staff member or official testing positive to coronavirus we will immediately suspend the series.

"I'm proud of our sport and the stance we have taken during this difficult time. We thank our teams, players, staff, officials and fans for their understanding and patience during what is a very challenging time for everybody and we wish both teams the best of the luck for the remainder of the series."

Perth currently leads the series 1–0.

Australian Medical Association WA president Andrew Miller welcomed news of the suspension of public gatherings, but said it was frustrating the measure was not being put in place immediately.

"In typical Government style it is not starting straight away," Dr Miller said.

"We are frustrated about that. We would encourage people that this weekend is just as important as Monday. We would say stay home, watch it on the telly.

"If it is not OK to do it on Monday, why is it OK to go on Saturday and Sunday?"

He said closing schools and universities should be the next phase.

"The schools … need a bit of preparation time but it will be coming," he said.

"Sometime in the next few weeks we would expect the Government would be looking closely at that.

"I suspect what will happen is that schools won't go back after the holidays.

"I think it is also time to look at tighter travel restrictions."

Cloud grows over Anzac Day services

On Thursday, the WA branch of the RSL (RSLWA) said there was a "very good possibility" it would be forced to cancel many Anzac Day services.

That scenario appeared even more likely to eventuate on Friday after the call for the suspension of gatherings of more than 500 people.

The RSLWA board will meet formally this weekend to discuss the issue, but CEO John McCourt conceded he had a duty of care to attendees, and would follow the Prime Minister's advice.

"It would follow wouldn't it that obviously for example in Perth, the major dawn service in Kings Park and the street parade and then the commemorative service, clearly that draws many, many more than 500 people," he said.

Bali travel concerns

At a meeting of Premiers and Chief Ministers in Sydney, WA Premier Mark McGowan flagged concerns about West Australians travelling to and from Bali.

He said Indonesia had been under-reporting cases of coronavirus and he believed action may need to be taken.

Premier Mark McGowan is worried about travel in and out of Bali. ( Sarina Locke: ABC Rural )

"My concerns have been growing over recent days," he said.

"Clearly there is under-reporting in Indonesia, so clearly we need to get proper advice and potentially take further action on that very soon."

Dr Robertson said he shared those concerns.

"I would strongly recommend that people look at whether they want to travel to Indonesia," he said.

"And also be aware that with a global pandemic declared, if they become unwell, their medical insurance may not cover them and they may have to look at how they will be managed in Bali if they become seriously unwell."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 56 seconds 3 m 56 s Will the coronavirus push Australia into recession? Alan Kohler takes a look ( Alan Kohler )

Mr Cook urged West Australians to reconsider all international travel plans.

"If I had international plans for travel today, I would cancel them unless it was absolutely essential," he said.

"I think we need to understand that the spread of this virus globally is now continuing at pace and it is important that people do everything they can to protect themselves."

Mr McGowan said in a Facebook post people should remain calm despite being in unchartered territory.

"I want to make it clear to Western Australians who are thinking about travelling overseas — this virus is spreading across the globe, and at a much faster rate in some countries," he wrote.

"If your overseas travel isn't an absolute requirement, please reconsider it. Explore our great state instead."