SJA medical director Paul Bailey says there have been times in recent months where only two spare ambulances were available in the metropolitan area, despite presentations to emergency departments falling during the COVID-19 pandemic.

He says the increase in ramping - where patients are kept in ambulances or on trolleys in corridors while waiting for beds - could be due to emergency departments being reconfigured to isolate potential COVID patients.

"In the last few weeks, things have pretty much gone back to normal and we're now seeing ramping at troubling levels again," he told 6PR radio on Wednesday.

"Some emergency departments are paying the price of trying to be COVID-safe for all of us."

Mr Bailey said the number of ramping hours across the system during July was almost triple that recorded five years ago, when the former Liberal government introduced a target for all ED patients to be admitted or discharged within four hours.

But Health Minister Roger Cook disputed claims of a return to excessive ramping.

"Our ambulance handover rates at the moment are around about 21 minutes which is a slight improvement on the 22 minutes from last year," Mr Cook told reporters.

"Our EDs are working well and our ambulance handover rates are doing better than ever ... obviously someone's not looking at the same numbers we are."

One new coronavirus case was recorded on Wednesday after a returned overseas traveller tested positive while in hotel quarantine.

WA has seven active cases.

Australia's deputy chief medical officer Nick Coatsworth this week appeared to suggest WA's hard border closures were not a proportionate response to its potential for an outbreak given case numbers had remained low.

"We respectfully disagree," Mr Cook said.

"The (WA) chief health officer has advised us that the biggest public health risk Western Australia faces today comes from people coming into the state, whether that is from overseas or from interstate ... we're very proud of our approach."

Australian Associated Press