A woman who works at a youth detention centre in Brisbane has reportedly tested positive for COVID-19.
Three close relatives of the 70-year-old have tested negative, Channel Nine reported.
Authorities are attempting to confirm what interaction she may have had with the young people detained inside the facility.
Queensland Health Minister Steven Miles refused to confirm the reports at a press conference earlier on Thursday until briefed by officials.
The latest case comes after a woman who stayed in Brisbane tested positive on returning to Japan, sparking a health alert.
The woman arrived in Australia in mid-July and quarantined in Sydney before coming to Brisbane.
A notification alert is active for Virgin flight VA962 from Brisbane to Sydney on August 17 and for anyone at The Jam Pantry cafe at Greenslopes on August 16.
"While in quarantine, she returned two negative test results," Dr Young said on Wednesday night.
"Because she quarantined in Sydney and travelled straight to Brisbane from hotel quarantine, she could go about her normal life in Brisbane."
"However on her arrival to Japan on 18 August, she was asymptomatic but tested positive."
Six close contacts of the woman in Brisbane have been tested and are now in quarantine, while tracing continues.
Queensland Chief Health Officer Dr Jeannette Young speaks to the media. Source: AAP
Those on the flight or who dined at the cafe have been told to monitor for symptoms and get tested if any develop.
In a Facebook post, the cafe's owners said they would be closing the venue for deep cleaning on Thursday.
The alert comes after a man who recently returned from Papua New Guinea became Queensland's latest case, prompting the state to beef up monitoring of its porous northern border.
The man in his 40s had been in hotel quarantine and tested positive on the seventh day of his 14-day isolation period.
Meanwhile, Premier Annastacia Palaszczuk again warned Queensland's border restrictions will continue for now, given the outbreaks in Victoria, NSW and New Zealand, despite federal government pressure.
The issue will be discussed further when the national cabinet of federal, state and territory leaders meets on Friday.
"We need to keep our measures in place," Ms Palaszczuk said.
