A worsening coronavirus outbreak in Sydney prompted Australian regions to pull up the drawbridge on the city and surrounding state Friday by implementing unprecedented travel restrictions.

Western Australia became the latest state to impose tighter curbs on travel from New South Wales and its state capital, which posted a record 390 new infections Friday.

Western Australia premier Mark McGowan said from Tuesday would-be travellers will have to secure an exemption to enter his state, provide a negative Covid test, show proof of at least one vaccine dose, undergo 14 days home quarantine and install a tracking app on their phone.

If Sydney's cases go above 500 a day, travellers will have to undergo a mandatory 14-day hotel quarantine and exemptions will be limited to a small number including the armed forces.

McGowan said the measures -- which are more restrictive than many international borders -- were "tough" but "entirely fair".

In Queensland, Premier Annastacia Palaszczuk said she was also "very very concerned" about the situation in New South Wales and warned that more border restrictions were on the way.

"No one should be crossing that border to go into New South Wales," she said. "We do not want to see this virus creeping north and if we have to implement harder measures we will."

A man sits in front of the Harbour Bridge and Opera House in Sydney. People are still allowed out for exercise, shopping, health care and essential work
A man sits in front of the Harbour Bridge and Opera House in Sydney. People are still allowed out for exercise, shopping, health care and essential work AFP / Saeed KHAN

There is growing anger at Sydney's failure to bring its seven-week-old outbreak under control, as cases spread to the countryside and across state borders.

More than 10 million Australians are in lockdown as the Sydney cluster -- which started with an overseas flight crew -- grew to 6,874 cases.

Authorities have indicated that a Sydney lockdown could remain in some form until October, but have refrained from further citywide restrictions.

Residents are still allowed to leave their homes for exercise, shopping, health care and essential work. Critics argue that is not restrictive enough.

As anger grows, Australian Prime Minister Scott Morrison backed Western Australia's move. "I do welcome the requirements for vaccination," he said.

Morrison's conservative government has largely delegated responsibility for the pandemic response to states.

Lockdowns, testing, travel restrictions and vaccine rollouts are mostly dictated by state governments who have often publicly bickered about strategy.

Coronavirus