Western Australia will demand arrivals from NSW prove they have had at least one dose of a coronavirus vaccine under tough new arrangements.
Travellers must also provide proof of a negative PCR test in the 72 hours prior to departure, Premier Mark McGowan announced on Friday.
The measures will come into effect from Tuesday when NSW will move to a beefed-up "high risk" category under WA's controlled border regime.
It comes as NSW on Friday reported 390 new locally-acquired cases and a further two deaths.
"Given what is happening in NSW, there's no sign of the situation improving over coming weeks," Mr McGowan told reporters.
"These are tough measures but they are necessary to protect the state. The situation in NSW is very serious and our hard border arrangements must reflect that and reduce the risk to Western Australians."
Scott Morrison backed the arrangements after Friday's national cabinet meeting.
"That is not unlike the sorts of things we have been talking about for some time, where people are vaccinated, and an exemption is being granted, but the vaccination aids that exemption being given on public health grounds," the prime minister said.
"I think that is very consistent with what the national plan is seeking to achieve, and as I said last week, all premiers and chief ministers strongly committed and agreed to the national plan."
But Mr Morrison warned that such measures should not be maintained once most Australians had been vaccinated.
"It's a decision for now, because borders exist now," he said.
"But in the future, the whole point of getting to 70 per cent and 80 per cent is to say, ultimately, goodbye to those arrangements as well."
Mr McGowan earlier wouldn't rule out keeping vaccine passports beyond that point if there were outbreaks in other states.
He said the tough new rules offered a template for other states to replicate.
"The legal advice is very clear that, based upon the advice of the chief health officer, this is entirely lawful," he added.
NSW, Victoria, Queensland and South Australia are already subject to a hard border, denying entry to the vast majority of travellers.
