The Northern Territory government has declared metropolitan Adelaide a coronavirus hotspot, effective from midnight on Tuesday.
It means anyone travelling from the South Australian capital to the NT will be required to go into supervised quarantine at facilities in Howard Springs or Alice Springs for 14 days.
The decision comes after the South Australian government announced the state would go into lockdown from 6:00pm on Tuesday to curb a COVID-19 outbreak.
Five cases of the Delta strain have been linked to the current cluster.
The South Australian lockdown will last for seven days.
In addition to the Adelaide hotspot, the Northern Territory currently has declarations in place across dozens of local government areas in Greater Sydney and its surrounds, Greater Melbourne, and Mildura in Victoria.
