CANBERRA - Australia's Prime Minister Scott Morrison has called an emergency meeting of state and territory leaders in an attempt to get the country's COVID-19 vaccine rollout back on track.

Morrison announced on Tuesday night that the National Cabinet, which is made up of the PM, state premiers, territory chief ministers, will meet twice a week from Monday to address the troubled rollout.

National Cabinet, which was established in response to the COVID-19 pandemic, has scaled back to one meeting per month in 2021.

In a statement announcing the changes Morrison acknowledged that the vaccine program was facing "serious challenges."

"There are serious challenges we need to overcome caused by patchy international vaccine -supplies, changing medical advice and a global environment of need caused by millions of COVID-19 cases and deaths," he said.

"I have requested that -national cabinet and our health ministers move back to an operational footing - to work together, closely, to tackle head on the challenges we are all facing with making our vaccination program as good as it can be," he said.

The federal government has abandoned its goal of vaccinating the Australian population by the end of October and has ruled out setting any further vaccine targets.

As of Tuesday more than 1.2 million Australians had received COVID-19 vaccines, less than half of the four million the government previously promised would be vaccinated by the end of March.

The rollout has been plagued by international supply issues and by concerns over the safety of the AstraZeneca vaccine.

Earlier in April medical regulators gave new advice about the AstraZeneca jab.

Australia's Chief Medical Officer Paul Kelly said that the Australian Technical Advisory Group on Immunization (ATAGI) recommended "the use of the Pfizer vaccine is preferred over the AstraZeneca vaccine in adults aged less than 50 years who have not already received a first dose of AstraZeneca vaccine."

It came after the Australian government asked the nation's medical regulator to further investigate links between AstraZeneca's coronavirus vaccine and blood-clotting issues.

Earlier on Wednesday Richard Marles, deputy leader of the opposition, accused the government of dodging responsibility for the vaccine rollout, saying that the country risks "watching the rest of the world open up while Australia has been left behind."

"Australian business is deeply concerned about what the future looks like in a world where we are at the back of the queue in terms of being vaccinated rather than at the front," he told media.

He said, "What we need to be hearing from the government is: what is the target, what are the milestones and what is the pathway out?"