A number of new border measures have been introduced by National Cabinet to combat further introduction of the mutant UK variant of the virus.

Australians wanting to return home from overseas will be forced to undergo pre-flight testing before boarding their planes.

Masks will be mandatory on all national and international flights.

In coming days the federal government will announce details of how the new testing regime will be carried out.

The states have refused to increase the intake of return travellers.

From midnight tonight South Australia will declare Greater Brisbane a hotspot, and travellers will be required to self-isolate for 14 days.

(Photo: iStock by Getty Images.)