A four-day lockdown in Western Australia is on track to finish on schedule after the state recorded no new coronavirus cases.

More than two million people in Perth and the Peel region are under lockdown until 12.01am on Saturday after local cases of the Delta variant were detected.

About 15,800 people got swabbed on Wednesday, a result Premier Mark McGowan described as “amazingly encouraging” while urging further testing.

“It puts WA in the best possible position, especially as our contact tracers continue to find potential contacts,” he said on Thursday.

“When it comes time to lift restrictions we want to be confident this incredibly infectious virus, the Delta variant, is not still in the community.

“The next 24 hours are crucial … we hope to have more to say about the next steps we are going to take tomorrow.”

The outbreak has been traced to a 51-year-old physiotherapist who recently returned to WA from NSW, where she contracted the Delta variant.

Infections were subsequently detected in two men aged in their 20s and 30s and a 32-year-old woman who attended various venues throughout Perth’s northern suburbs.

Of 360 close contacts identified to date, 295 have so far tested negative, as have 1173 out of 2503 casual contacts.

Mr McGowan said he had been made aware of tourists flaunting restrictions and entering vulnerable remote Aboriginal communities in the Kimberley.

“This is completely unacceptable, not only for the health of local Aboriginal people but it is also disrespectful to those communities,” he said.

“No one wants a COVID outbreak in a remote Aboriginal community. Tourists need to follow the rules like everyone else.”

Health Minister Roger Cook confirmed inmates and staff at WA’s prisons would receive the Pfizer vaccine in coming weeks.

“Should COVID-19 enter a prison, it would go through that prison like wildfire,” he said.

The lockdown in Perth and Peel is the third in five months.

Tourism operators have warned they face significant financial losses with school holidays set to begin on Saturday.

A business support package is yet to be finalised.

-AAP