SYDNEY - Australia recorded its worst day in the coronavirus pandemic on Thursday as the country's second-most populous state reported more than 700 new infections and 13 deaths.

The previous national record of new cases was 518 but a second wave in Victoria centered on aged care facilities has forced authorities to lock down state capital Melbourne and other states to close their borders.

"I'm obviously concerned to see these numbers increase. It is not unexpected in some ways when you have got so many cases in private sector aged care," Victorian Premier Daniel Andrews told reporters in Melbourne.

Too many people were going to work when they were sick or while they were waiting for test results, he added.

Social distancing restrictions would be extended, with residents the state's south no longer allowed to have visitors to their homes from late Thursday.

Everyone in the state will from Sunday also be required to wear a mask when outside.

Earlier this month, Victoria told nearly 5 million people around Melbourne, the country's second-most-populous city, to wear masks outside and stay home except for essential trips.

The outbreak in Victoria state has spilled into neighboring states despite internal borders being closed.

Queensland state on Thursday said it had found three new cases, two of whom were believed to have contracted COVID-19 while in Sydney, the capital of New South Wales state.