Queensland has added three new cases to its tally, for a total of 1088 with 11 active.
Premier Annastacia Palaszczuk said one new case in a 68-year-old Ipswich woman was still “under investigation”, with two further historic cases also added to the total.
Queensland authorities say the decision to close the border to the ACT as well was based on evidence that some were flying from the smaller state to bypass Sydney hotspot declarations.
State disaster co-ordinator Steve Gollschewski pointed to one example where one man drove from Sydney and then flew to Cairns via Brisbane.
“Whilst our system is working quite well, we recognise that we cannot keep that up with the types of numbers that are coming,” he said.
Deputy Premier Steven Miles said border restrictions had been some of the most “effective tools” at stopping COVID-19 coming into the state and urged Clive Palmer to drop his “dangerous and reckless” case against closures.