South Australia has declared the greater Brisbane area a COVID-19 hotspot, preventing travel into the state to all but returning residents and essential workers.
Premier Steven Marshall says the new rules will apply from 4pm on Monday.
"We are extraordinarily concerned about the developing situation in Queensland," Mr Marshall said.
"Obviously Queensland authorities are moving very, very quickly now.
"But some of the people testing positive for the coronavirus have been out and about more broadly in Brisbane."
SA will also require anyone who arrived in Adelaide from Brisbane from March 20 to immediately get tested and isolate until they receive a negative result.
Anyone who arrived between March 11 and March 20 is asked to get tested if they have any virus symptoms.
Returning SA residents will be required to quarantine for 14 days.
