Scott Morrison says the government will consider limiting the number of people allowed to return to Australia in the coming weeks, as a second wave spreads across Melbourne.

Since March, more than 350,000 Australians have returned home - with a majority of these travellers undergoing mandatory quarantine in hotels in Sydney and Melbourne.

However, the system is currently "under pressure", said the PM, who suggested future arrivals may have to pay for their own quarantine.

At the weekend, Sydney Airport capped the number of international arrivals to 450 a day.

Yesterday New Zealand announced a pause on citizens booking flights home, as they are also nearing capacity in their quarantine system.