MELBOURNE/SYDNEY (REUTERS) - Australian Prime Minister Scott Morrison warned on Wednesday (April 15) the nation's children could become the silent victims of the coronavirus pandemic, as officials investigate new nursing home cluster.

Australia's rate of new Covid-19 infections has been sustained at levels much lower than other countries for weeks, but the country has so far retained strict social distancing rules that have closed businesses and confined people to their homes.

Still, Mr Morrison urged teachers to return to classrooms across the country to join "great heroes" like medical staffand supermarket workers, stressing the risk that children from disadvantaged families in particular lose a year of education.

"At this time, as our nation fights this coronavirus, your role has become even more important," Mr Morrison said in an videod address posted on his official Facebook page. "The education of our children hangs in the balance."

The Australian leader's plea risks reopening cracks between the federal government and various state jurisdictions over the thorny issue of whether children should be attending school while much of the country is in lockdown mode.

Mr Morrison said that official health advice has consistently deemed the risks to children from attending school to be very low, but some state leaders have urged parents to keep children at home while trade unions have highlighted the risks to teachers.

Australia has reported around 6,400 cases of Covid-19, the disease caused by the new coronavirus, and 61 deaths, with the rate of daily increases in the low single digits for weeks although there have been a handful of new clusters over the past week.

Two hospitals in Tasmania account for more than a third of the country's recent new cases.

Treasurer Josh Frydenberg referred to the low new infection rate when addressing International Monetary Fund (IMF) released overnight that Australia's economy would contract by 6.7 per cent this year, before rebounding in 2021 with growth of 6.1 per cent.

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The IMF also predicted a rise in Australian unemployment to 7.6 per cent this year and to 8.9 per cent next year.

"At the time the IMF were putting together their figures, the Australian curve was heading in the wrong direction if you like," Mr Frydenberg said. "We were seeing an exponential increase of more than 20 per cent a day ... Since that time, we've bent that curve and we're seeing a growth of less than 2 per cent per day and our health measures are making significant progress."

CRUISE SHIP PROBE

Ten cases have been identified at the facility run by charity Anglicare in western Sydney, New South Wales, that include six staff and four residents, after a staff member went to work while infected, the state's chief health officer said.

"This person is absolutely mortified. I would urge people to remember that the symptoms of Covid can be incredibly mild and the key point is do not go to work," Dr Kerry Chant told a televised media briefing.

Also in New South Wales state, Premier Gladys Berejiklian announced a new special commission inquiry into how coronavirus-infected passengers were allowed to disembark a cruise ship in Sydney a month ago was given extra powers by the New South Wales government on Wednesday.

The new probe bolsters an already announced police investigation into the Ruby Princess, which has been linked to 18 deaths and hundreds of infections.