WA Premier Mark McGowan has lambasted the federal government for failing to provide better alternatives to hotel quarantine.

Metropolitan Perth and the neighbouring Peel region are currently in a three-day lockdown after COVID-19 cases linked to the Perth Mercure Hotel.

Mr McGowan said CBD hotels were not fit for purpose and that defence facilities such as Curtin Air Base in Derby or immigration detention facilities on Christmas Island would be better.

But Mr Dutton, the federal defence minister, disagrees.

"I'd love to tell you that air bases or the Christmas Island facility is fit for purpose but it is not," he told ABC's Insiders program on Sunday.

"Mark McGowan has made a mistake with the Mercure Hotel. Nobody is being critical of him for that. He doesn't need to be defensive. He doesn't want to be the next Dan Andrews where they had significant problems," he added, referring to Victoria's long lockdown last year.

He said the premiers agreed last year on medical advice to conduct the hotel quarantining the way they are doing.

Mr McGowan said on Sunday the Commonwealth had agreed to his request to half the number of returned travellers to 512 per week for a least a month.

"If the Commonwealth is unable to assist with proper quarantine facilities, I am reluctant to return to the full 1025 per week cap," Mr McGowan told reporters.

"That weekly number of returning residents is not something that can continue long term without proper Commonwealth quarantine facilities being used."

There were no new locally acquired cases reported in WA on Sunday, but two new infections - one a returned traveller in hotel quarantine, the other a WA resident who was a close contact of a case now in Victoria. They are also in hotel quarantine.

However, more potential exposure sites have been added to the list.

"Right now it's too early to predict what will happen come Tuesday," Mr McGowan said, referring to when the lockdown is due to end.

"We need to see more testing completed."

Despite the uncertainty caused by lockdowns across the country and a slow vaccine rollout, Australians are snapping up half-price flights under a $1.2 billion package to help tourism bounce back from the pandemic.

Deputy Prime Minister Michael McCormack says 600,000 flights have been booked in just three weeks out of the 800,000 that were on offer.

"Australians are taking trips in large numbers with airlines reporting sales dwarfing previous records - our aviation industry is in a remarkable position compared to where it was just one year ago," Mr McCormack said in a statement on Sunday.

Meanwhile, AstraZeneca shots will be available for people over 50 at state and territory vaccination centres as well as respiratory clinics from May 3, before being sent to all GPs from May 17.

Even so, Labor's spokesman for the NDIS Bill Shorten is not happy at the extremely slow pace of vaccination at disability facilities, saying just 100 out of 6000 facilities have received their jabs.

"The federal government has got one job in 2021, to roll out the vaccine so that life can get back to normal," Mr Shorten told Sky News' Sunday Agenda program.

"What have they been doing for the last 12 months? How can 100 countries have done better than Australia?"

The nation's two largest states reported no new locally acquired COVID-19 cases on Sunday, although both had one new infection among returned overseas travellers already in quarantine

Australian Associated Press