Scott Morrison has rejected blame for Victoria's extended lockdown amid renewed pressure on his government over quarantine and the vaccine rollout.
Melbourne's restrictions will now last until June 10, while rules in regional Victoria will ease from Thursday night.
Labor has blamed the federal government's failure to take charge of quarantine for returning travellers and the sluggish vaccine rollout for the extended lockdown.
Mr Morrison refused to accept responsibility for contributing to the restrictions designed to curb an outbreak that has infected 61 people with the Indian variant of coronavirus.
"Decisions to implement lockdowns in states and territories around the country are solely and totally the responsibility of state and territory governments," he told parliament.
The prime minister and Treasurer Josh Frydenberg will speak with their Victorian counterparts after the state government pleaded for more support.
The federal government is refusing to revive JobKeeper wage subsidies for Victoria where some businesses and workers are prevented from earning money.
"We will stick to our principles, namely, our approaches will continue to be national, sustainable, where support is offered it is through existing systems," Mr Frydenberg told reporters in Canberra.
The federal treasurer pointed to business tax relief in the budget as assistance which anticipated further lockdowns.
Labor's Jim Chalmers said the coalition should agree to the state government's request for financial support for thousands of workers not receiving a pay cheque.
"The Morrison government's failures on vaccines and quarantine are strangling the small businesses of Victoria," the shadow treasurer told reporters.
"What we're seeing in Victoria today is the consequence of a prime minister who fails to take responsibility for quarantine and cannot get the vaccinations away."
There are also renewed calls for an overhaul of hotel quarantine after a man in Perth became infected by a fellow returned traveller in a room next door.
Respected health adviser Jane Halton, who undertook a major review of quarantine, said recent breaches in hotels were because her recommendations were not being adopted.
"I'm disappointed that it certainly appears that we don't have continual adoption of best practice right across the system," she told ABC radio.
"To say that I'm disappointed about that I think is the minimum."
Ms Halton said it was perplexing it had taken so long to increase capacity at the Howard Springs quarantine camp in the NT and look at facilities in other states.
Talks between the Victorian and federal governments are understood to be progressing on a stand-alone quarantine facility, likely to be based near Avalon Airport.
The Australian Medical Association is calling for urgent quarantine changes after the latest Perth infection, the 21st recorded breach in hotels.
Victoria's coronavirus outbreak is continuing to grow across more than 350 exposure sites.
The federal government has vowed to fix a data blind spot which has left them without knowledge of how many aged care workers have been vaccinated.
While the rollout remains behind schedule, there were 700,000 doses administered in the past seven-day reporting period, signalling a ramped up jab rate.