Australia will quarantine people who arrive from overseas in hotels for two weeks in an attempt to slow the spread of the coronavirus.

From 11.59pm on Saturday, all overseas arrivals to the country will be forcibly quarantined in hotels and other accomodation. People will be quarantined in the city in which they arrive, regardless of where they live.

The measures will be enforced by the states and territories with assistance from the Australian Defence Force.

Until now, overseas travellers had been asked to self-isolate for 14 days.

Announcing the change on Friday, Scott Morrison said two thirds of the COVID-19 cases in the country were from Australians who had travelled home from overseas.

“We have just over 3,000 cases in Australia. We are worried. We are worried about the growth,” said chief medical officer Brendan Murphy.

“Our numbers have not been helped by a recent cruise ship,” Murphy added, speaking of the infamous Ruby Princess.

Last week, Australia and New Zealand closed their borders to all but citizens, residents and direct family members.

The numbers of travellers has dropped dramatically, Morrison said. “Yesterday there was 7,120 arrivals at our airports around the country. To give you an idea of what that was this same time last year, it was 48,725.”