Australian public life could be constrained for another year because of the coronavirus pandemic, Prime Minister Scott Morrison warned on Friday, as the country's most populous state mulled sending children to school in shifts.

Australia has so far avoided the high numbers of coronavirus casualties reported around the world after closing its borders and imposing strict "social distancing" measures for the past months.

"Social distancing is something we should get very used to," Morrison told radio station 3AW. "It could be a year, but I'm not speculating about that."

Restaurants, bars and other "non-essential" businesses have closed and public gatherings of more than two people are banned under the threat of fines and even prison, which are expected to double the unemployment rate by mid-year.

Morrison also said several wider social distancing measures will stay for at least another four weeks while advocating reopening schools across the country, citing medical advice that children are a low risk of transmission.

The Prime Minister has tightened physical distancing restrictions on March 29 to prevent further spread of COVID-19, but how people will follow the rules will be determined by the guideline of each state.

Queensland has announced a public health emergency, only allowing residents to leave their home for essential reasons. Also, the state border has closed since 3 April to everyone except residents and essential workers. New South Wales has also adopted a two-person gathering limit.

To track the COVID-19 victims and people who might come in contact with them, the government has planned to introduce a smartphone app, which is being used in Singapore.

The mobile phone app has been criticized by civil liberties groups but Morrison declined to rule out making it mandatory, saying the rollout would be voluntary at first so Australians have "the opportunity to get it right."

(With input from Xinhua, 3 AW Radio Station and Reuters)