Australia's second-largest city Melbourne reinstated COVID-19 restrictions on Tuesday as authorities scrambled to find the missing link in a fresh outbreak, prompting New Zealand to pause a "travel bubble" with the state of Victoria.
Amid worries the cluster, which has grown to nine cases in two days, could spark a major outbreak, Victoria imposed social restrictions and made face masks mandatory in hotels, restaurants, and other indoor venues from 6 p.m. (0800 GMT) on Tuesday until June 4.
The latest outbreak ends Victoria's run of zero cases for nearly three months and saw New Zealand suspend quarantine-free travel with the state and the neighboring state of South Australia impose travel restrictions.
Australia has avoided the high COVID-19 numbers seen in many developed countries by closing its international borders in the early stages of the pandemic and with lockdowns. It has reported just over 30,000 cases and 910 deaths.
Thousands of people in Melbourne have been ordered to self-isolate and undergo COVID-19 tests with health alerts issued for several sites, including one of the largest shopping centers in the country.
One of the cases had a high viral load while he visited some venues prompting authorities to warn Melbourne's five million residents to brace for more positive cases in the next few days.
Authorities urged Victorians to get vaccinated.