Western Australia’s Premier has defended the state’s slow coronavirus vaccine take-up as he maintains his tough stance on borders and lockdowns.

It came as WA said from Tuesday it would demand arrivals from virus-plagued NSW provide a negative test and prove they have had at least one vaccine dose.

It will be a future requirement for any states and territories recording an average of more than 50 daily community cases.

On Monday, mining magnate Clive Palmer said he would launch another High Court challenge against WA over the vaccine passport policy.

The billionaire, who previously failed to overturn WA’s hard border closures, has questioned the effectiveness of coronavirus vaccines.

“By restricting free movement of Australian citizens within Australia and creating an island-within-an-island, the WA COVID-19 eradication strategy is unconstitutional,” Mr Palmer said.

WA will expand its vaccine rollout from Monday, with people aged 16 to 29 invited to booking to get the Pfizer vaccine.

More than two million West Australians are eligible, with Pfizer reserved for under 60s and others to continue receiving the AstraZeneca jab.

WA’s vaccine rollout has been the slowest of any state or territory. Just 22.5 per cent of people aged 16 and over have received both jabs.

It comes as Premier Mark McGowan faces backlash for suggesting WA will continue to pursue a strategy of zero community transmission.

He says border closures and targeted lockdowns will remain options even when 80 per cent of the population has been vaccinated.

“We will do what’s required to keep the people of our state safe,” he said on Monday.

Mr McGowan said the national roadmap included scope for “highly-targeted lockdowns” at phase C, when 80 per cent of people were vaccinated.

National leaders agreed that states should retain the right to implement domestic border closures and that position had been accepted by the High Court, he said.

Mr McGowan bristled when asked what incentive people would have for getting vaccinated if the threat of lockdowns and border closures continued.

“We are following the national roadmap. It’s there in black and white,” he said.

“If we have 80 per cent vaccination we still have 20 per cent of eligible people unvaccinated. That’s 400,000 people … some of them may well be very vulnerable.

“My view is, people in this state want the right to stay safe.

“In terms of vaccination I’d encourage, as we do every day, people to go and get vaccinated.”

Mr McGowan said while NSW and Victoria had both endured months of lockdowns, West Australians had been confined for a total of 12 days during the pandemic and were now enjoying total freedoms within the borders.

The modelling behind the national roadmap indicated states would need to reintroduce restrictions on gatherings before easing border closures.

“We’d need to have lower crowds at stadiums, we’d need to have social distancing measures … I’m pretty keen to avoid that,” he said.

Prime Minister Scott Morrison earlier said the promise of removing restrictions was a key incentive for people to get vaccinated.

“Australians are working hard, making sacrifices, getting vaccinated, being subjected to lockdowns,” he told Sky News.

“Now, they’re all doing this for a reason – to get on the path out, and the path out is set out in that national plan.”

-AAP