Australia will limit the number of people arriving in the country by air to a maximum of 4,000 per week "for the foreseeable future", Prime Minister Scott Morrison said during a press conference after three states featuring key international gateways enforced their own limits.

The cap entered into effect on July 13 and marks a reduction by around half compared to more recent levels of arrivals into Australia by air. Since March, only Australian citizens, as well as permanent residents and their immediate family members have been allowed to enter.

Morrison's nationwide cap follows earlier steps taken by the governments of three key states. Following a fresh spike in cases around Melbourne, the government of Victoria banned all international arrivals into Melbourne Tullamarine through July 15. As passengers rebooked onto flights arriving at Sydney Kingsford Smith, the government of New South Wales, facing the growing costs of a state-funded two-week quarantine for all arrivals, said it would limit the number of passengers arriving in Sydney from abroad to 50 per flight and 450 per week through July 17.

In turn, the government of Western Australia capped the number of international arrivals at Perth International to 75 per day and 525 per week.

While in most of Australia, local governments have continued to fund accommodation and meals for quarantined arrivals, Queensland - which did not limit the number of people arriving from abroad at Brisbane International - has started charging quarantined persons as of July 1. Morrison suggested that as a part of a review of the whole system, a "user-pays" principle could soon be implemented in other states, too.