On Friday, the national cabinet meets to consider limits on international arrivals to slow numbers, and changes to the hotel quarantine system that might also require arrivals to start paying for their own quarantine.

In Victoria, authorities have eased the rules for residents of eight of the nine public housing towers, who are now under the same stay-at-home order as the rest of Melbourne, but can leave for essential work, essential shopping and exercise.

But the ninth tower will be kept in hard lockdown for another nine days, after 53 people tested positive, with residents not allowed to leave their home other than for supervised daily exercise. Victoria's chief health officer Brett Sutton said as many as one in four residents in that tower might end up with the virus.

Case numbers in the tower were high enough that everyone was considered a close contact, Premier Daniel Andrews said. People who had tested positive would be offered accommodation elsewhere.

In all 2515 residents of the towers had been tested, with 159 positives.

Remaining residents who had refused a test would have to remain isolated.

South Australia is making testing and masks compulsory for everyone who crosses into the state.

Queensland opens its borders on Friday to Canberrans and people from states other than Victoria, but anyone going to Queensland will need to prove they haven't been to Victoria for 14 days.

Western Australia announced on Thursday afternoon that its border would be hardened still further.

No-one would be allowed in if they had been in Victoria for the previous 14 days unless they fell into a strict list of exemptions that had been narrowed to transport and freight workers and workers approved by state emergency authorities, the state's Health Minister, Roger Cook, said.

Everyone allowed in under the new rules must do a COVID-19 test on their 11th day.

Western Australian authorities said companies, including in the mining, oil and gas industries, have been told they must find workers from places other than Victoria.

In the ACT, with four cases now diagnosed among people returned from Melbourne and contacts, Victorians are asked to apply for exemptions to travel here. Once in Canberra, they are asked to self-isolate for two weeks.

Victoria's 165 cases on Thursday follows 134 the day before and 191 the day before that. The state has now recorded 1300 new cases in 15 days. Victoria's chief health office Brett Sutton said the outbreak was unlikely to have peaked.

Prime Minister Scott Morrison confirmed his acting Immigration Minister Alan Tudge was given permission to travel from Melbourne to Canberra this week.

Mr Tudge was in Canberra to announce new visas for Hong Kong students, skilled migrants and businesses, and the end of the extradition treaty with Hong Kong.

Mr Morrison said the ACT government had allowed Mr Tudge in "under quite strict conditions".

He did not elaborate, and Mr Tudge's office would not provide details of his exemption, referring questions about conditions to the ACT government. He returned to Melbourne on Thursday.

ACT chief health officer Kerryn Coleman said all applications for essential workers were being treated the same.

Federal parliamentarians would need to demonstrate their work was essential and could not be postponed.

They must include a risk mitigation plan, showing how they had reduced their risk of exposure in Melbourne and how they proposed to reduce the risk of transmission in Canberra if they were infectious.

For staffers to travel, they would have to submit a declaration demonstrating that they were essential, she said.

ACT Chief Minister Andrew Barr has said ministers will be given exemptions as essential workers, but staffers and others are still being negotiated.

The major parties and parliamentary authorities are yet to say how many exemptions they will be requesting.

Melburnian and Treasurer Josh Frydenberg was already in Canberra when the border closed.

Health Minister Greg Hunt is also from Melbourne, along with Mr Tudge.

Education Minister Dan Tehan has a coastal electorate to the west of Melbourne and Defence Personnel Minister Darren Chester to the east.

Mr Frydenberg is due to deliver a budget update in Canberra in two weeks, on July 23.

Parliament resumes in the first week of August.

Three cases have now been announced in Albury, with NSW Premier Gladys Berejiklian said saying Melbourne was believed to be the source. One of the three had travelled to greater Melbourne and the other two were linked.

The other 11 cases diagnosed in NSW in the 24 hours to 8pm on Wednesday were all in hotel quarantine.

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Ms Berejiklian said NSW would not tighten restrictions on gatherings yet but was on high alert for seeding of cases from Victoria.

"What we find comforting is that in the last 24 hours 18,500 people did come forward to get testing. And given the extremely low rate of community transmission there is no science-based reason for us to change anything at this stage," Ms Berejiklian said.

"All I'm saying to everybody is please be on high alert. What we're doing is taking the science, taking the evidence and advice on a daily basis, and if we need to move on anything we will.

"At this stage there is no evidence to suggest we need to, but we won't know or a few weeks whether there has been any seeding ... community transmission bubbling away under the surface."

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