Authorities in Australia's second most populous state warned the next few days would be critical to preventing a coronavirus outbreak after a man in his 30s tested positive a day earlier for Covid-19.

The unidentified man was the first locally transmitted case in Victoria state in more than two months. Health officials said it was most likely he contracted the virus while serving his 14-day hotel quarantine in neighbouring South Australia state.

“So far, we have just had the one positive case but the next day or two would be critical,” Victoria state Health Minister Martin Foley told reporters in Melbourne as he confirmed there were no new cases in the state over the past 24 hours.